15 files changed, 817 insertions, 140 deletions

diff --git a/crates/ra_ide/src/goto_definition.rs b/crates/ra_ide/src/goto_definition.rs
index a6c86e99c..0798d2c36 100644
--- a/crates/ra_ide/src/goto_definition.rs
+++ b/crates/ra_ide/src/goto_definition.rs
@@ -1,6 +1,6 @@
 use hir::Semantics;
 use ra_ide_db::{
-    defs::{classify_name, classify_name_ref},
+    defs::{classify_name, classify_name_ref, NameClass},
     symbol_index, RootDatabase,
 };
 use ra_syntax::{
@@ -39,7 +39,10 @@ pub(crate) fn goto_definition(
                 reference_definition(&sema, &name_ref).to_vec()
             },
             ast::Name(name) => {
-                let def = classify_name(&sema, &name)?.definition();
+                let def = match classify_name(&sema, &name)? {
+                    NameClass::Definition(def) | NameClass::ConstReference(def) => def,
+                    NameClass::FieldShorthand { local: _, field } => field,
+                };
                 let nav = def.try_to_nav(sema.db)?;
                 vec![nav]
             },
@@ -886,4 +889,23 @@ mod tests {
             "x",
         )
     }
+
+    #[test]
+    fn goto_def_for_enum_variant_field() {
+        check_goto(
+            "
+            //- /lib.rs
+            enum Foo {
+                Bar { x: i32 }
+            }
+            fn baz(foo: Foo) {
+                match foo {
+                    Foo::Bar { x<|> } => x
+                };
+            }
+            ",
+            "x RECORD_FIELD_DEF FileId(1) 21..27 21..22",
+            "x: i32|x",
+        );
+    }
 }
diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index 9636cd0d6..ad78b7671 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -13,14 +13,52 @@ use ra_ide_db::{
 use ra_syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset};
 
 use crate::{
-    display::{macro_label, rust_code_markup, rust_code_markup_with_doc, ShortLabel},
-    FilePosition, RangeInfo,
+    display::{macro_label, rust_code_markup, rust_code_markup_with_doc, ShortLabel, ToNav},
+    runnables::runnable,
+    FileId, FilePosition, NavigationTarget, RangeInfo, Runnable,
 };
+use test_utils::mark;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct HoverConfig {
+    pub implementations: bool,
+    pub run: bool,
+    pub debug: bool,
+}
+
+impl Default for HoverConfig {
+    fn default() -> Self {
+        Self { implementations: true, run: true, debug: true }
+    }
+}
+
+impl HoverConfig {
+    pub const NO_ACTIONS: Self = Self { implementations: false, run: false, debug: false };
+
+    pub fn any(&self) -> bool {
+        self.implementations || self.runnable()
+    }
+
+    pub fn none(&self) -> bool {
+        !self.any()
+    }
+
+    pub fn runnable(&self) -> bool {
+        self.run || self.debug
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum HoverAction {
+    Runnable(Runnable),
+    Implementaion(FilePosition),
+}
 
 /// Contains the results when hovering over an item
 #[derive(Debug, Default)]
 pub struct HoverResult {
     results: Vec<String>,
+    actions: Vec<HoverAction>,
 }
 
 impl HoverResult {
@@ -48,10 +86,20 @@ impl HoverResult {
         &self.results
     }
 
+    pub fn actions(&self) -> &[HoverAction] {
+        &self.actions
+    }
+
+    pub fn push_action(&mut self, action: HoverAction) {
+        self.actions.push(action);
+    }
+
     /// Returns the results converted into markup
     /// for displaying in a UI
+    ///
+    /// Does not process actions!
     pub fn to_markup(&self) -> String {
-        self.results.join("\n\n---\n")
+        self.results.join("\n\n___\n")
     }
 }
 
@@ -82,6 +130,14 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
         res.extend(hover_text_from_name_kind(db, name_kind));
 
         if !res.is_empty() {
+            if let Some(action) = show_implementations_action(db, name_kind) {
+                res.push_action(action);
+            }
+
+            if let Some(action) = runnable_action(&sema, name_kind, position.file_id) {
+                res.push_action(action);
+            }
+
             return Some(RangeInfo::new(range, res));
         }
     }
@@ -112,6 +168,56 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
     Some(RangeInfo::new(range, res))
 }
 
+fn show_implementations_action(db: &RootDatabase, def: Definition) -> Option<HoverAction> {
+    fn to_action(nav_target: NavigationTarget) -> HoverAction {
+        HoverAction::Implementaion(FilePosition {
+            file_id: nav_target.file_id(),
+            offset: nav_target.range().start(),
+        })
+    }
+
+    match def {
+        Definition::ModuleDef(it) => match it {
+            ModuleDef::Adt(Adt::Struct(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Adt(Adt::Union(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Adt(Adt::Enum(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Trait(it) => Some(to_action(it.to_nav(db))),
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
+fn runnable_action(
+    sema: &Semantics<RootDatabase>,
+    def: Definition,
+    file_id: FileId,
+) -> Option<HoverAction> {
+    match def {
+        Definition::ModuleDef(it) => match it {
+            ModuleDef::Module(it) => match it.definition_source(sema.db).value {
+                ModuleSource::Module(it) => runnable(&sema, it.syntax().clone(), file_id)
+                    .map(|it| HoverAction::Runnable(it)),
+                _ => None,
+            },
+            ModuleDef::Function(it) => {
+                let src = it.source(sema.db);
+                if src.file_id != file_id.into() {
+                    mark::hit!(hover_macro_generated_struct_fn_doc_comment);
+                    mark::hit!(hover_macro_generated_struct_fn_doc_attr);
+
+                    return None;
+                }
+
+                runnable(&sema, src.value.syntax().clone(), file_id)
+                    .map(|it| HoverAction::Runnable(it))
+            }
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
 fn hover_text(
     docs: Option<String>,
     desc: Option<String>,
@@ -228,6 +334,9 @@ fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
 
 #[cfg(test)]
 mod tests {
+    use super::*;
+    use insta::assert_debug_snapshot;
+
     use ra_db::FileLoader;
     use ra_syntax::TextRange;
 
@@ -241,7 +350,15 @@ mod tests {
         s.map(trim_markup)
     }
 
-    fn check_hover_result(fixture: &str, expected: &[&str]) -> String {
+    fn assert_impl_action(action: &HoverAction, position: u32) {
+        let offset = match action {
+            HoverAction::Implementaion(pos) => pos.offset,
+            it => panic!("Unexpected hover action: {:#?}", it),
+        };
+        assert_eq!(offset, position.into());
+    }
+
+    fn check_hover_result(fixture: &str, expected: &[&str]) -> (String, Vec<HoverAction>) {
         let (analysis, position) = analysis_and_position(fixture);
         let hover = analysis.hover(position).unwrap().unwrap();
         let mut results = Vec::from(hover.info.results());
@@ -256,7 +373,7 @@ mod tests {
         assert_eq!(hover.info.len(), expected.len());
 
         let content = analysis.db.file_text(position.file_id);
-        content[hover.range].to_string()
+        (content[hover.range].to_string(), hover.info.actions().to_vec())
     }
 
     fn check_hover_no_result(fixture: &str) {
@@ -457,7 +574,7 @@ struct Test<K, T = u8> {
 }
 
 fn main() {
-    let zz<|> = Test { t: 23, k: 33 };
+    let zz<|> = Test { t: 23u8, k: 33 };
 }"#,
             &["Test<i32, u8>"],
         );
@@ -746,7 +863,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_macro() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             "
             //- /lib.rs
             macro_rules! id {
@@ -767,7 +884,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_expr_in_macro() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             "
             //- /lib.rs
             macro_rules! id {
@@ -785,7 +902,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_expr_in_macro_recursive() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             "
             //- /lib.rs
             macro_rules! id_deep {
@@ -806,7 +923,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_func_in_macro_recursive() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             "
             //- /lib.rs
             macro_rules! id_deep {
@@ -830,7 +947,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_literal_string_in_macro() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             r#"
             //- /lib.rs
             macro_rules! arr {
@@ -849,7 +966,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_assert_macro() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             r#"
             //- /lib.rs
             #[rustc_builtin_macro]
@@ -925,13 +1042,14 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_trait_show_qualifiers() {
-        check_hover_result(
+        let (_, actions) = check_hover_result(
             "
             //- /lib.rs
             unsafe trait foo<|>() {}
             ",
             &["unsafe trait foo"],
         );
+        assert_impl_action(&actions[0], 13);
     }
 
     #[test]
@@ -1003,6 +1121,8 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_macro_generated_struct_fn_doc_comment() {
+        mark::check!(hover_macro_generated_struct_fn_doc_comment);
+
         check_hover_result(
             r#"
             //- /lib.rs
@@ -1029,6 +1149,8 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_macro_generated_struct_fn_doc_attr() {
+        mark::check!(hover_macro_generated_struct_fn_doc_attr);
+
         check_hover_result(
             r#"
             //- /lib.rs
@@ -1052,4 +1174,140 @@ fn func(foo: i32) { if true { <|>foo; }; }
             &["Bar\n```\n\n```rust\nfn foo(&self)\n```\n___\n\nDo the foo"],
         );
     }
+
+    #[test]
+    fn test_hover_trait_has_impl_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            trait foo<|>() {}
+            ",
+            &["trait foo"],
+        );
+        assert_impl_action(&actions[0], 6);
+    }
+
+    #[test]
+    fn test_hover_struct_has_impl_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            struct foo<|>() {}
+            ",
+            &["struct foo"],
+        );
+        assert_impl_action(&actions[0], 7);
+    }
+
+    #[test]
+    fn test_hover_union_has_impl_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            union foo<|>() {}
+            ",
+            &["union foo"],
+        );
+        assert_impl_action(&actions[0], 6);
+    }
+
+    #[test]
+    fn test_hover_enum_has_impl_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            enum foo<|>() {
+                A,
+                B
+            }
+            ",
+            &["enum foo"],
+        );
+        assert_impl_action(&actions[0], 5);
+    }
+
+    #[test]
+    fn test_hover_test_has_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            #[test]
+            fn foo_<|>test() {}
+            ",
+            &["fn foo_test()"],
+        );
+        assert_debug_snapshot!(actions,
+            @r###"
+            [
+                Runnable(
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 0..24,
+                            name: "foo_test",
+                            kind: FN_DEF,
+                            focus_range: Some(
+                                11..19,
+                            ),
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "foo_test",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [],
+                    },
+                ),
+            ]
+            "###);
+    }
+
+    #[test]
+    fn test_hover_test_mod_has_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            mod tests<|> {
+                #[test]
+                fn foo_test() {}
+            }
+            ",
+            &["mod tests"],
+        );
+        assert_debug_snapshot!(actions,
+            @r###"
+            [
+                Runnable(
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 0..46,
+                            name: "tests",
+                            kind: MODULE,
+                            focus_range: Some(
+                                4..9,
+                            ),
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: TestMod {
+                            path: "tests",
+                        },
+                        cfg_exprs: [],
+                    },
+                ),
+            ]
+            "###);
+    }
 }
diff --git a/crates/ra_ide/src/inlay_hints.rs b/crates/ra_ide/src/inlay_hints.rs
index 75bd3c96b..7eb2cef73 100644
--- a/crates/ra_ide/src/inlay_hints.rs
+++ b/crates/ra_ide/src/inlay_hints.rs
@@ -149,11 +149,10 @@ fn get_param_name_hints(
         ast::Expr::MethodCallExpr(expr) => expr.arg_list()?.args(),
         _ => return None,
     };
-    let args_count = args.clone().count();
 
     let fn_signature = get_fn_signature(sema, &expr)?;
     let n_params_to_skip =
-        if fn_signature.has_self_param && fn_signature.parameter_names.len() > args_count {
+        if fn_signature.has_self_param && matches!(&expr, ast::Expr::MethodCallExpr(_)) {
             1
         } else {
             0
@@ -416,7 +415,7 @@ struct Test<K, T = u8> {
 }
 
 fn main() {
-    let zz = Test { t: 23, k: 33 };
+    let zz = Test { t: 23u8, k: 33 };
     let zz_ref = &zz;
 }"#,
         );
@@ -429,7 +428,7 @@ fn main() {
                 label: "Test<i32>",
             },
             InlayHint {
-                range: 105..111,
+                range: 107..113,
                 kind: TypeHint,
                 label: "&Test<i32>",
             },
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index 12d5716e8..a56718d3f 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -66,7 +66,7 @@ pub use crate::{
     display::{file_structure, FunctionSignature, NavigationTarget, StructureNode},
     expand_macro::ExpandedMacro,
     folding_ranges::{Fold, FoldKind},
-    hover::HoverResult,
+    hover::{HoverAction, HoverConfig, HoverResult},
     inlay_hints::{InlayHint, InlayHintsConfig, InlayKind},
     references::{Declaration, Reference, ReferenceAccess, ReferenceKind, ReferenceSearchResult},
     runnables::{Runnable, RunnableKind, TestId},
@@ -77,7 +77,7 @@ pub use crate::{
 };
 
 pub use hir::Documentation;
-pub use ra_assists::{AssistConfig, AssistId};
+pub use ra_assists::{Assist, AssistConfig, AssistId, ResolvedAssist};
 pub use ra_db::{
     Canceled, CrateGraph, CrateId, Edition, FileId, FilePosition, FileRange, SourceRootId,
 };
@@ -142,14 +142,6 @@ pub struct AnalysisHost {
     db: RootDatabase,
 }
 
-#[derive(Debug)]
-pub struct Assist {
-    pub id: AssistId,
-    pub label: String,
-    pub group_label: Option<String>,
-    pub source_change: SourceChange,
-}
-
 impl AnalysisHost {
     pub fn new(lru_capacity: Option<usize>) -> AnalysisHost {
         AnalysisHost { db: RootDatabase::new(lru_capacity) }
@@ -470,20 +462,23 @@ impl Analysis {
         self.with_db(|db| completion::completions(db, config, position).map(Into::into))
     }
 
-    /// Computes assists (aka code actions aka intentions) for the given
+    /// Computes resolved assists with source changes for the given position.
+    pub fn resolved_assists(
+        &self,
+        config: &AssistConfig,
+        frange: FileRange,
+    ) -> Cancelable<Vec<ResolvedAssist>> {
+        self.with_db(|db| ra_assists::Assist::resolved(db, config, frange))
+    }
+
+    /// Computes unresolved assists (aka code actions aka intentions) for the given
     /// position.
-    pub fn assists(&self, config: &AssistConfig, frange: FileRange) -> Cancelable<Vec<Assist>> {
-        self.with_db(|db| {
-            ra_assists::Assist::resolved(db, config, frange)
-                .into_iter()
-                .map(|assist| Assist {
-                    id: assist.assist.id,
-                    label: assist.assist.label,
-                    group_label: assist.assist.group.map(|it| it.0),
-                    source_change: assist.source_change,
-                })
-                .collect()
-        })
+    pub fn unresolved_assists(
+        &self,
+        config: &AssistConfig,
+        frange: FileRange,
+    ) -> Cancelable<Vec<Assist>> {
+        self.with_db(|db| Assist::unresolved(db, config, frange))
     }
 
     /// Computes the set of diagnostics for the given file.
diff --git a/crates/ra_ide/src/runnables.rs b/crates/ra_ide/src/runnables.rs
index f32ce0d22..fc57dc33d 100644
--- a/crates/ra_ide/src/runnables.rs
+++ b/crates/ra_ide/src/runnables.rs
@@ -11,14 +11,14 @@ use ra_syntax::{
 
 use crate::{display::ToNav, FileId, NavigationTarget};
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct Runnable {
     pub nav: NavigationTarget,
     pub kind: RunnableKind,
     pub cfg_exprs: Vec<CfgExpr>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum TestId {
     Name(String),
     Path(String),
@@ -33,7 +33,7 @@ impl fmt::Display for TestId {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum RunnableKind {
     Test { test_id: TestId, attr: TestAttr },
     TestMod { path: String },
@@ -42,6 +42,42 @@ pub enum RunnableKind {
     Bin,
 }
 
+#[derive(Debug, Eq, PartialEq)]
+pub struct RunnableAction {
+    pub run_title: &'static str,
+    pub debugee: bool,
+}
+
+const TEST: RunnableAction = RunnableAction { run_title: "▶\u{fe0e} Run Test", debugee: true };
+const DOCTEST: RunnableAction =
+    RunnableAction { run_title: "▶\u{fe0e} Run Doctest", debugee: false };
+const BENCH: RunnableAction = RunnableAction { run_title: "▶\u{fe0e} Run Bench", debugee: true };
+const BIN: RunnableAction = RunnableAction { run_title: "▶\u{fe0e} Run", debugee: true };
+
+impl Runnable {
+    // test package::module::testname
+    pub fn label(&self, target: Option<String>) -> String {
+        match &self.kind {
+            RunnableKind::Test { test_id, .. } => format!("test {}", test_id),
+            RunnableKind::TestMod { path } => format!("test-mod {}", path),
+            RunnableKind::Bench { test_id } => format!("bench {}", test_id),
+            RunnableKind::DocTest { test_id, .. } => format!("doctest {}", test_id),
+            RunnableKind::Bin => {
+                target.map_or_else(|| "run binary".to_string(), |t| format!("run {}", t))
+            }
+        }
+    }
+
+    pub fn action(&self) -> &'static RunnableAction {
+        match &self.kind {
+            RunnableKind::Test { .. } | RunnableKind::TestMod { .. } => &TEST,
+            RunnableKind::DocTest { .. } => &DOCTEST,
+            RunnableKind::Bench { .. } => &BENCH,
+            RunnableKind::Bin => &BIN,
+        }
+    }
+}
+
 // Feature: Run
 //
 // Shows a popup suggesting to run a test/benchmark/binary **at the current cursor
@@ -59,7 +95,11 @@ pub(crate) fn runnables(db: &RootDatabase, file_id: FileId) -> Vec<Runnable> {
     source_file.syntax().descendants().filter_map(|i| runnable(&sema, i, file_id)).collect()
 }
 
-fn runnable(sema: &Semantics<RootDatabase>, item: SyntaxNode, file_id: FileId) -> Option<Runnable> {
+pub(crate) fn runnable(
+    sema: &Semantics<RootDatabase>,
+    item: SyntaxNode,
+    file_id: FileId,
+) -> Option<Runnable> {
     match_ast! {
         match item {
             ast::FnDef(it) => runnable_fn(sema, it, file_id),
@@ -135,7 +175,7 @@ fn runnable_fn(
     Some(Runnable { nav, kind, cfg_exprs })
 }
 
-#[derive(Debug)]
+#[derive(Debug, Copy, Clone)]
 pub struct TestAttr {
     pub ignore: bool,
 }
@@ -207,6 +247,15 @@ mod tests {
 
     use crate::mock_analysis::analysis_and_position;
 
+    use super::{Runnable, RunnableAction, BENCH, BIN, DOCTEST, TEST};
+
+    fn assert_actions(runnables: &[Runnable], actions: &[&RunnableAction]) {
+        assert_eq!(
+            actions,
+            runnables.into_iter().map(|it| it.action()).collect::<Vec<_>>().as_slice()
+        );
+    }
+
     #[test]
     fn test_runnables() {
         let (analysis, pos) = analysis_and_position(
@@ -221,6 +270,9 @@ mod tests {
         #[test]
         #[ignore]
         fn test_foo() {}
+
+        #[bench]
+        fn bench() {}
         "#,
         );
         let runnables = analysis.runnables(pos.file_id).unwrap();
@@ -295,9 +347,32 @@ mod tests {
                 },
                 cfg_exprs: [],
             },
+            Runnable {
+                nav: NavigationTarget {
+                    file_id: FileId(
+                        1,
+                    ),
+                    full_range: 82..104,
+                    name: "bench",
+                    kind: FN_DEF,
+                    focus_range: Some(
+                        94..99,
+                    ),
+                    container_name: None,
+                    description: None,
+                    docs: None,
+                },
+                kind: Bench {
+                    test_id: Path(
+                        "bench",
+                    ),
+                },
+                cfg_exprs: [],
+            },
         ]
         "###
                 );
+        assert_actions(&runnables, &[&BIN, &TEST, &TEST, &BENCH]);
     }
 
     #[test]
@@ -361,6 +436,7 @@ mod tests {
         ]
         "###
                 );
+        assert_actions(&runnables, &[&BIN, &DOCTEST]);
     }
 
     #[test]
@@ -427,6 +503,7 @@ mod tests {
         ]
         "###
                 );
+        assert_actions(&runnables, &[&BIN, &DOCTEST]);
     }
 
     #[test]
@@ -493,6 +570,7 @@ mod tests {
         ]
         "###
                 );
+        assert_actions(&runnables, &[&TEST, &TEST]);
     }
 
     #[test]
@@ -561,6 +639,7 @@ mod tests {
         ]
         "###
                 );
+        assert_actions(&runnables, &[&TEST, &TEST]);
     }
 
     #[test]
@@ -631,6 +710,7 @@ mod tests {
         ]
         "###
                 );
+        assert_actions(&runnables, &[&TEST, &TEST]);
     }
 
     #[test]
@@ -681,6 +761,7 @@ mod tests {
         ]
         "###
                 );
+        assert_actions(&runnables, &[&TEST]);
     }
 
     #[test]
@@ -739,6 +820,7 @@ mod tests {
         ]
         "###
                 );
+        assert_actions(&runnables, &[&TEST]);
     }
 
     #[test]
diff --git a/crates/ra_ide/src/snapshots/highlight_doctest.html b/crates/ra_ide/src/snapshots/highlight_doctest.html
new file mode 100644
index 000000000..0ae8c7efc
--- /dev/null
+++ b/crates/ra_ide/src/snapshots/highlight_doctest.html
@@ -0,0 +1,71 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+</style>
+<pre><code><span class="keyword">impl</span> <span class="unresolved_reference">Foo</span> {
+    <span class="comment">/// Constructs a new `Foo`.</span>
+    <span class="comment">///</span>
+    <span class="comment">/// # Examples</span>
+    <span class="comment">///</span>
+    <span class="comment">/// ```</span>
+    <span class="comment">/// #</span> <span class="attribute">#![</span><span class="function attribute">allow</span><span class="attribute">(unused_mut)]</span>
+    <span class="comment">/// </span><span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">foo</span>: <span class="unresolved_reference">Foo</span> = <span class="unresolved_reference">Foo</span>::<span class="unresolved_reference">new</span>();
+    <span class="comment">/// ```</span>
+    <span class="keyword">pub</span> <span class="keyword">const</span> <span class="keyword">fn</span> <span class="function declaration">new</span>() -&gt; <span class="unresolved_reference">Foo</span> {
+        <span class="unresolved_reference">Foo</span> { }
+    }
+
+    <span class="comment">/// `bar` method on `Foo`.</span>
+    <span class="comment">///</span>
+    <span class="comment">/// # Examples</span>
+    <span class="comment">///</span>
+    <span class="comment">/// ```</span>
+    <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">foo</span> = <span class="unresolved_reference">Foo</span>::<span class="unresolved_reference">new</span>();
+    <span class="comment">///</span>
+    <span class="comment">/// </span><span class="comment">// calls bar on foo</span>
+    <span class="comment">/// </span><span class="macro">assert!</span>(foo.bar());
+    <span class="comment">///</span>
+    <span class="comment">/// </span><span class="comment">/* multi-line
+    </span><span class="comment">/// </span><span class="comment">       comment */</span>
+    <span class="comment">///</span>
+    <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">multi_line_string</span> = <span class="string_literal">"Foo
+    </span><span class="comment">/// </span><span class="string_literal">  bar
+    </span><span class="comment">/// </span><span class="string_literal">         "</span>;
+    <span class="comment">///</span>
+    <span class="comment">/// ```</span>
+    <span class="comment">///</span>
+    <span class="comment">/// ```</span>
+    <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">foobar</span> = <span class="unresolved_reference">Foo</span>::<span class="unresolved_reference">new</span>().<span class="unresolved_reference">bar</span>();
+    <span class="comment">/// ```</span>
+    <span class="keyword">pub</span> <span class="keyword">fn</span> <span class="function declaration">foo</span>(&<span class="self_keyword">self</span>) -&gt; <span class="builtin_type">bool</span> {
+        <span class="bool_literal">true</span>
+    }
+}</code></pre>
\ No newline at end of file
diff --git a/crates/ra_ide/src/snapshots/highlight_injection.html b/crates/ra_ide/src/snapshots/highlight_injection.html
index fcdc98201..dec06eb51 100644
--- a/crates/ra_ide/src/snapshots/highlight_injection.html
+++ b/crates/ra_ide/src/snapshots/highlight_injection.html
@@ -10,7 +10,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .string_literal     { color: #CC9393; }
 .field              { color: #94BFF3; }
 .function           { color: #93E0E3; }
-.operator.unsafe    { color: #E28C14; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
 .parameter          { color: #94BFF3; }
 .text               { color: #DCDCCC; }
 .type               { color: #7CB8BB; }
diff --git a/crates/ra_ide/src/snapshots/highlight_strings.html b/crates/ra_ide/src/snapshots/highlight_strings.html
index e97192b61..849eb3b73 100644
--- a/crates/ra_ide/src/snapshots/highlight_strings.html
+++ b/crates/ra_ide/src/snapshots/highlight_strings.html
@@ -10,7 +10,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .string_literal     { color: #CC9393; }
 .field              { color: #94BFF3; }
 .function           { color: #93E0E3; }
-.operator.unsafe    { color: #E28C14; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
 .parameter          { color: #94BFF3; }
 .text               { color: #DCDCCC; }
 .type               { color: #7CB8BB; }
@@ -63,7 +64,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="macro">println!</span>(<span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">^</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span>, <span class="string_literal">"x"</span>);
     <span class="macro">println!</span>(<span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">&gt;</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span>, <span class="string_literal">"x"</span>);
     <span class="macro">println!</span>(<span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">+</span><span class="format_specifier">}</span><span class="string_literal">!"</span>, <span class="numeric_literal">5</span>);
-    <span class="macro">println!</span>(<span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">#</span><span class="variable">x</span><span class="string_literal">}!"</span>, <span class="numeric_literal">27</span>);
+    <span class="macro">println!</span>(<span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">#</span><span class="variable">x</span><span class="format_specifier">}</span><span class="string_literal">!"</span>, <span class="numeric_literal">27</span>);
     <span class="macro">println!</span>(<span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="numeric_literal">0</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span>, <span class="numeric_literal">5</span>);
     <span class="macro">println!</span>(<span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="numeric_literal">0</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span>, -<span class="numeric_literal">5</span>);
     <span class="macro">println!</span>(<span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">#</span><span class="numeric_literal">0</span><span class="numeric_literal">10</span><span class="variable">x</span><span class="format_specifier">}</span><span class="string_literal">!"</span>, <span class="numeric_literal">27</span>);
diff --git a/crates/ra_ide/src/snapshots/highlight_unsafe.html b/crates/ra_ide/src/snapshots/highlight_unsafe.html
index 17ffc727c..bd24e6e38 100644
--- a/crates/ra_ide/src/snapshots/highlight_unsafe.html
+++ b/crates/ra_ide/src/snapshots/highlight_unsafe.html
@@ -10,7 +10,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .string_literal     { color: #CC9393; }
 .field              { color: #94BFF3; }
 .function           { color: #93E0E3; }
-.operator.unsafe    { color: #E28C14; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
 .parameter          { color: #94BFF3; }
 .text               { color: #DCDCCC; }
 .type               { color: #7CB8BB; }
@@ -42,7 +43,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="keyword unsafe">unsafe</span> {
         <span class="function unsafe">unsafe_fn</span>();
         <span class="struct">HasUnsafeFn</span>.<span class="function unsafe">unsafe_method</span>();
-        <span class="keyword">let</span> <span class="variable declaration">y</span> = <span class="operator unsafe">*</span><span class="variable">x</span>;
+        <span class="keyword">let</span> <span class="variable declaration">y</span> = <span class="operator unsafe">*</span>(<span class="variable">x</span>);
         <span class="keyword">let</span> <span class="variable declaration">z</span> = -<span class="variable">x</span>;
     }
 }</code></pre>
\ No newline at end of file
diff --git a/crates/ra_ide/src/snapshots/highlighting.html b/crates/ra_ide/src/snapshots/highlighting.html
index 42c5f3e55..e34ff5a7d 100644
--- a/crates/ra_ide/src/snapshots/highlighting.html
+++ b/crates/ra_ide/src/snapshots/highlighting.html
@@ -10,7 +10,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .string_literal     { color: #CC9393; }
 .field              { color: #94BFF3; }
 .function           { color: #93E0E3; }
-.operator.unsafe    { color: #E28C14; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
 .parameter          { color: #94BFF3; }
 .text               { color: #DCDCCC; }
 .type               { color: #7CB8BB; }
diff --git a/crates/ra_ide/src/snapshots/rainbow_highlighting.html b/crates/ra_ide/src/snapshots/rainbow_highlighting.html
index 2dd61d20d..1ab06182c 100644
--- a/crates/ra_ide/src/snapshots/rainbow_highlighting.html
+++ b/crates/ra_ide/src/snapshots/rainbow_highlighting.html
@@ -10,7 +10,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .string_literal     { color: #CC9393; }
 .field              { color: #94BFF3; }
 .function           { color: #93E0E3; }
-.operator.unsafe    { color: #E28C14; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
 .parameter          { color: #94BFF3; }
 .text               { color: #DCDCCC; }
 .type               { color: #7CB8BB; }
diff --git a/crates/ra_ide/src/syntax_highlighting.rs b/crates/ra_ide/src/syntax_highlighting.rs
index 19ecd54d6..ab45c364a 100644
--- a/crates/ra_ide/src/syntax_highlighting.rs
+++ b/crates/ra_ide/src/syntax_highlighting.rs
@@ -1,5 +1,6 @@
 mod tags;
 mod html;
+mod injection;
 #[cfg(test)]
 mod tests;
 
@@ -10,14 +11,14 @@ use ra_ide_db::{
 };
 use ra_prof::profile;
 use ra_syntax::{
-    ast::{self, HasFormatSpecifier, HasQuotes, HasStringValue},
+    ast::{self, HasFormatSpecifier},
     AstNode, AstToken, Direction, NodeOrToken, SyntaxElement,
     SyntaxKind::*,
-    SyntaxToken, TextRange, WalkEvent, T,
+    TextRange, WalkEvent, T,
 };
 use rustc_hash::FxHashMap;
 
-use crate::{call_info::ActiveParameter, Analysis, FileId};
+use crate::FileId;
 
 use ast::FormatSpecifier;
 pub(crate) use html::highlight_as_html;
@@ -123,6 +124,23 @@ pub(crate) fn highlight(
             _ => (),
         }
 
+        // Check for Rust code in documentation
+        match &event {
+            WalkEvent::Leave(NodeOrToken::Node(node)) => {
+                if let Some((doctest, range_mapping, new_comments)) =
+                    injection::extract_doc_comments(node)
+                {
+                    injection::highlight_doc_comment(
+                        doctest,
+                        range_mapping,
+                        new_comments,
+                        &mut stack,
+                    );
+                }
+            }
+            _ => (),
+        }
+
         let element = match event {
             WalkEvent::Enter(it) => it,
             WalkEvent::Leave(_) => continue,
@@ -173,7 +191,7 @@ pub(crate) fn highlight(
 
         if let Some(token) = element.as_token().cloned().and_then(ast::RawString::cast) {
             let expanded = element_to_highlight.as_token().unwrap().clone();
-            if highlight_injection(&mut stack, &sema, token, expanded).is_some() {
+            if injection::highlight_injection(&mut stack, &sema, token, expanded).is_some() {
                 continue;
             }
         }
@@ -259,9 +277,8 @@ impl HighlightedRangeStack {
             let mut parent = prev.pop().unwrap();
             for ele in children {
                 assert!(parent.range.contains_range(ele.range));
-                let mut cloned = parent.clone();
-                parent.range = TextRange::new(parent.range.start(), ele.range.start());
-                cloned.range = TextRange::new(ele.range.end(), cloned.range.end());
+
+                let cloned = Self::intersect(&mut parent, &ele);
                 if !parent.range.is_empty() {
                     prev.push(parent);
                 }
@@ -274,6 +291,62 @@ impl HighlightedRangeStack {
         }
     }
 
+    /// Intersects the `HighlightedRange` `parent` with `child`.
+    /// `parent` is mutated in place, becoming the range before `child`.
+    /// Returns the range (of the same type as `parent`) *after* `child`.
+    fn intersect(parent: &mut HighlightedRange, child: &HighlightedRange) -> HighlightedRange {
+        assert!(parent.range.contains_range(child.range));
+
+        let mut cloned = parent.clone();
+        parent.range = TextRange::new(parent.range.start(), child.range.start());
+        cloned.range = TextRange::new(child.range.end(), cloned.range.end());
+
+        cloned
+    }
+
+    /// Similar to `pop`, but can modify arbitrary prior ranges (where `pop`)
+    /// can only modify the last range currently on the stack.
+    /// Can be used to do injections that span multiple ranges, like the
+    /// doctest injection below.
+    /// If `delete` is set to true, the parent range is deleted instead of
+    /// intersected.
+    ///
+    /// Note that `pop` can be simulated by `pop_and_inject(false)` but the
+    /// latter is computationally more expensive.
+    fn pop_and_inject(&mut self, delete: bool) {
+        let mut children = self.stack.pop().unwrap();
+        let prev = self.stack.last_mut().unwrap();
+        children.sort_by_key(|range| range.range.start());
+        prev.sort_by_key(|range| range.range.start());
+
+        for child in children {
+            if let Some(idx) =
+                prev.iter().position(|parent| parent.range.contains_range(child.range))
+            {
+                let cloned = Self::intersect(&mut prev[idx], &child);
+                let insert_idx = if delete || prev[idx].range.is_empty() {
+                    prev.remove(idx);
+                    idx
+                } else {
+                    idx + 1
+                };
+                prev.insert(insert_idx, child);
+                if !delete && !cloned.range.is_empty() {
+                    prev.insert(insert_idx + 1, cloned);
+                }
+            } else if let Some(_idx) =
+                prev.iter().position(|parent| parent.range.contains(child.range.start()))
+            {
+                unreachable!("child range should be completely contained in parent range");
+            } else {
+                let idx = prev
+                    .binary_search_by_key(&child.range.start(), |range| range.range.start())
+                    .unwrap_or_else(|x| x);
+                prev.insert(idx, child);
+            }
+        }
+    }
+
     fn add(&mut self, range: HighlightedRange) {
         self.stack
             .last_mut()
@@ -363,6 +436,7 @@ fn highlight_element(
                     highlight_name(db, def) | HighlightModifier::Definition
                 }
                 Some(NameClass::ConstReference(def)) => highlight_name(db, def),
+                Some(NameClass::FieldShorthand { .. }) => HighlightTag::Field.into(),
                 None => highlight_name_by_syntax(name) | HighlightModifier::Definition,
             }
         }
@@ -406,12 +480,8 @@ fn highlight_element(
                 _ => h,
             }
         }
-        PREFIX_EXPR => {
-            let prefix_expr = element.into_node().and_then(ast::PrefixExpr::cast)?;
-            match prefix_expr.op_kind() {
-                Some(ast::PrefixOp::Deref) => {}
-                _ => return None,
-            }
+        T![*] => {
+            let prefix_expr = element.parent().and_then(ast::PrefixExpr::cast)?;
 
             let expr = prefix_expr.expr()?;
             let ty = sema.type_of_expr(&expr)?;
@@ -539,42 +609,3 @@ fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
 
     tag.into()
 }
-
-fn highlight_injection(
-    acc: &mut HighlightedRangeStack,
-    sema: &Semantics<RootDatabase>,
-    literal: ast::RawString,
-    expanded: SyntaxToken,
-) -> Option<()> {
-    let active_parameter = ActiveParameter::at_token(&sema, expanded)?;
-    if !active_parameter.name.starts_with("ra_fixture") {
-        return None;
-    }
-    let value = literal.value()?;
-    let (analysis, tmp_file_id) = Analysis::from_single_file(value);
-
-    if let Some(range) = literal.open_quote_text_range() {
-        acc.add(HighlightedRange {
-            range,
-            highlight: HighlightTag::StringLiteral.into(),
-            binding_hash: None,
-        })
-    }
-
-    for mut h in analysis.highlight(tmp_file_id).unwrap() {
-        if let Some(r) = literal.map_range_up(h.range) {
-            h.range = r;
-            acc.add(h)
-        }
-    }
-
-    if let Some(range) = literal.close_quote_text_range() {
-        acc.add(HighlightedRange {
-            range,
-            highlight: HighlightTag::StringLiteral.into(),
-            binding_hash: None,
-        })
-    }
-
-    Some(())
-}
diff --git a/crates/ra_ide/src/syntax_highlighting/html.rs b/crates/ra_ide/src/syntax_highlighting/html.rs
index 7d946c98d..5bada6252 100644
--- a/crates/ra_ide/src/syntax_highlighting/html.rs
+++ b/crates/ra_ide/src/syntax_highlighting/html.rs
@@ -69,7 +69,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .string_literal     { color: #CC9393; }
 .field              { color: #94BFF3; }
 .function           { color: #93E0E3; }
-.operator.unsafe    { color: #E28C14; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
 .parameter          { color: #94BFF3; }
 .text               { color: #DCDCCC; }
 .type               { color: #7CB8BB; }
diff --git a/crates/ra_ide/src/syntax_highlighting/injection.rs b/crates/ra_ide/src/syntax_highlighting/injection.rs
new file mode 100644
index 000000000..3575a0fc6
--- /dev/null
+++ b/crates/ra_ide/src/syntax_highlighting/injection.rs
@@ -0,0 +1,168 @@
+//! Syntax highlighting injections such as highlighting of documentation tests.
+
+use std::{collections::BTreeMap, convert::TryFrom};
+
+use ast::{HasQuotes, HasStringValue};
+use hir::Semantics;
+use ra_syntax::{ast, AstToken, SyntaxNode, SyntaxToken, TextRange, TextSize};
+use stdx::SepBy;
+
+use crate::{call_info::ActiveParameter, Analysis, HighlightTag, HighlightedRange, RootDatabase};
+
+use super::HighlightedRangeStack;
+
+pub(super) fn highlight_injection(
+    acc: &mut HighlightedRangeStack,
+    sema: &Semantics<RootDatabase>,
+    literal: ast::RawString,
+    expanded: SyntaxToken,
+) -> Option<()> {
+    let active_parameter = ActiveParameter::at_token(&sema, expanded)?;
+    if !active_parameter.name.starts_with("ra_fixture") {
+        return None;
+    }
+    let value = literal.value()?;
+    let (analysis, tmp_file_id) = Analysis::from_single_file(value);
+
+    if let Some(range) = literal.open_quote_text_range() {
+        acc.add(HighlightedRange {
+            range,
+            highlight: HighlightTag::StringLiteral.into(),
+            binding_hash: None,
+        })
+    }
+
+    for mut h in analysis.highlight(tmp_file_id).unwrap() {
+        if let Some(r) = literal.map_range_up(h.range) {
+            h.range = r;
+            acc.add(h)
+        }
+    }
+
+    if let Some(range) = literal.close_quote_text_range() {
+        acc.add(HighlightedRange {
+            range,
+            highlight: HighlightTag::StringLiteral.into(),
+            binding_hash: None,
+        })
+    }
+
+    Some(())
+}
+
+/// Mapping from extracted documentation code to original code
+type RangesMap = BTreeMap<TextSize, TextSize>;
+
+/// Extracts Rust code from documentation comments as well as a mapping from
+/// the extracted source code back to the original source ranges.
+/// Lastly, a vector of new comment highlight ranges (spanning only the
+/// comment prefix) is returned which is used in the syntax highlighting
+/// injection to replace the previous (line-spanning) comment ranges.
+pub(super) fn extract_doc_comments(
+    node: &SyntaxNode,
+) -> Option<(String, RangesMap, Vec<HighlightedRange>)> {
+    // wrap the doctest into function body to get correct syntax highlighting
+    let prefix = "fn doctest() {\n";
+    let suffix = "}\n";
+    // Mapping from extracted documentation code to original code
+    let mut range_mapping: RangesMap = BTreeMap::new();
+    let mut line_start = TextSize::try_from(prefix.len()).unwrap();
+    let mut is_doctest = false;
+    // Replace the original, line-spanning comment ranges by new, only comment-prefix
+    // spanning comment ranges.
+    let mut new_comments = Vec::new();
+    let doctest = node
+        .children_with_tokens()
+        .filter_map(|el| el.into_token().and_then(ast::Comment::cast))
+        .filter(|comment| comment.kind().doc.is_some())
+        .filter(|comment| {
+            if comment.text().contains("```") {
+                is_doctest = !is_doctest;
+                false
+            } else {
+                is_doctest
+            }
+        })
+        .map(|comment| {
+            let prefix_len = comment.prefix().len();
+            let line: &str = comment.text().as_str();
+            let range = comment.syntax().text_range();
+
+            // whitespace after comment is ignored
+            let pos = if let Some(ws) = line.chars().nth(prefix_len).filter(|c| c.is_whitespace()) {
+                prefix_len + ws.len_utf8()
+            } else {
+                prefix_len
+            };
+
+            // lines marked with `#` should be ignored in output, we skip the `#` char
+            let pos = if let Some(ws) = line.chars().nth(pos).filter(|&c| c == '#') {
+                pos + ws.len_utf8()
+            } else {
+                pos
+            };
+
+            range_mapping.insert(line_start, range.start() + TextSize::try_from(pos).unwrap());
+            new_comments.push(HighlightedRange {
+                range: TextRange::new(
+                    range.start(),
+                    range.start() + TextSize::try_from(pos).unwrap(),
+                ),
+                highlight: HighlightTag::Comment.into(),
+                binding_hash: None,
+            });
+            line_start += range.len() - TextSize::try_from(pos).unwrap();
+            line_start += TextSize::try_from('\n'.len_utf8()).unwrap();
+
+            line[pos..].to_owned()
+        })
+        .sep_by("\n")
+        .to_string();
+
+    if doctest.is_empty() {
+        return None;
+    }
+
+    let doctest = format!("{}{}{}", prefix, doctest, suffix);
+    Some((doctest, range_mapping, new_comments))
+}
+
+/// Injection of syntax highlighting of doctests.
+pub(super) fn highlight_doc_comment(
+    text: String,
+    range_mapping: RangesMap,
+    new_comments: Vec<HighlightedRange>,
+    stack: &mut HighlightedRangeStack,
+) {
+    let (analysis, tmp_file_id) = Analysis::from_single_file(text);
+
+    stack.push();
+    for mut h in analysis.highlight(tmp_file_id).unwrap() {
+        // Determine start offset and end offset in case of multi-line ranges
+        let mut start_offset = None;
+        let mut end_offset = None;
+        for (line_start, orig_line_start) in range_mapping.range(..h.range.end()).rev() {
+            if line_start <= &h.range.start() {
+                start_offset.get_or_insert(orig_line_start - line_start);
+                break;
+            } else {
+                end_offset.get_or_insert(orig_line_start - line_start);
+            }
+        }
+        if let Some(start_offset) = start_offset {
+            h.range = TextRange::new(
+                h.range.start() + start_offset,
+                h.range.end() + end_offset.unwrap_or(start_offset),
+            );
+            stack.add(h);
+        }
+    }
+
+    // Inject the comment prefix highlight ranges
+    stack.push();
+    for comment in new_comments {
+        stack.add(comment);
+    }
+    stack.pop_and_inject(false);
+    stack.pop_and_inject(true);
+}
diff --git a/crates/ra_ide/src/syntax_highlighting/tests.rs b/crates/ra_ide/src/syntax_highlighting/tests.rs
index 36a1aa419..021f8e7e2 100644
--- a/crates/ra_ide/src/syntax_highlighting/tests.rs
+++ b/crates/ra_ide/src/syntax_highlighting/tests.rs
@@ -7,9 +7,21 @@ use crate::{
     FileRange, TextRange,
 };
 
+/// Highlights the code given by the `ra_fixture` argument, renders the
+/// result as HTML, and compares it with the HTML file given as `snapshot`.
+/// Note that the `snapshot` file is overwritten by the rendered HTML.
+fn check_highlighting(ra_fixture: &str, snapshot: &str, rainbow: bool) {
+    let (analysis, file_id) = single_file(ra_fixture);
+    let dst_file = project_dir().join(snapshot);
+    let actual_html = &analysis.highlight_as_html(file_id, rainbow).unwrap();
+    let expected_html = &read_text(&dst_file);
+    fs::write(dst_file, &actual_html).unwrap();
+    assert_eq_text!(expected_html, actual_html);
+}
+
 #[test]
 fn test_highlighting() {
-    let (analysis, file_id) = single_file(
+    check_highlighting(
         r#"
 #[derive(Clone, Debug)]
 struct Foo {
@@ -84,17 +96,14 @@ impl<T> Option<T> {
 }
 "#
         .trim(),
+        "crates/ra_ide/src/snapshots/highlighting.html",
+        false,
     );
-    let dst_file = project_dir().join("crates/ra_ide/src/snapshots/highlighting.html");
-    let actual_html = &analysis.highlight_as_html(file_id, false).unwrap();
-    let expected_html = &read_text(&dst_file);
-    fs::write(dst_file, &actual_html).unwrap();
-    assert_eq_text!(expected_html, actual_html);
 }
 
 #[test]
 fn test_rainbow_highlighting() {
-    let (analysis, file_id) = single_file(
+    check_highlighting(
         r#"
 fn main() {
     let hello = "hello";
@@ -110,12 +119,9 @@ fn bar() {
 }
 "#
         .trim(),
+        "crates/ra_ide/src/snapshots/rainbow_highlighting.html",
+        true,
     );
-    let dst_file = project_dir().join("crates/ra_ide/src/snapshots/rainbow_highlighting.html");
-    let actual_html = &analysis.highlight_as_html(file_id, true).unwrap();
-    let expected_html = &read_text(&dst_file);
-    fs::write(dst_file, &actual_html).unwrap();
-    assert_eq_text!(expected_html, actual_html);
 }
 
 #[test]
@@ -153,7 +159,7 @@ fn test_ranges() {
 
 #[test]
 fn test_flattening() {
-    let (analysis, file_id) = single_file(
+    check_highlighting(
         r##"
 fn fixture(ra_fixture: &str) {}
 
@@ -167,13 +173,9 @@ fn main() {
     );
 }"##
         .trim(),
+        "crates/ra_ide/src/snapshots/highlight_injection.html",
+        false,
     );
-
-    let dst_file = project_dir().join("crates/ra_ide/src/snapshots/highlight_injection.html");
-    let actual_html = &analysis.highlight_as_html(file_id, false).unwrap();
-    let expected_html = &read_text(&dst_file);
-    fs::write(dst_file, &actual_html).unwrap();
-    assert_eq_text!(expected_html, actual_html);
 }
 
 #[test]
@@ -192,7 +194,7 @@ macro_rules! test {}
 fn test_string_highlighting() {
     // The format string detection is based on macro-expansion,
     // thus, we have to copy the macro definition from `std`
-    let (analysis, file_id) = single_file(
+    check_highlighting(
         r#"
 macro_rules! println {
     ($($arg:tt)*) => ({
@@ -250,18 +252,14 @@ fn main() {
     println!("{ничоси}", ничоси = 92);
 }"#
         .trim(),
+        "crates/ra_ide/src/snapshots/highlight_strings.html",
+        false,
     );
-
-    let dst_file = project_dir().join("crates/ra_ide/src/snapshots/highlight_strings.html");
-    let actual_html = &analysis.highlight_as_html(file_id, false).unwrap();
-    let expected_html = &read_text(&dst_file);
-    fs::write(dst_file, &actual_html).unwrap();
-    assert_eq_text!(expected_html, actual_html);
 }
 
 #[test]
 fn test_unsafe_highlighting() {
-    let (analysis, file_id) = single_file(
+    check_highlighting(
         r#"
 unsafe fn unsafe_fn() {}
 
@@ -276,16 +274,63 @@ fn main() {
     unsafe {
         unsafe_fn();
         HasUnsafeFn.unsafe_method();
-        let y = *x;
+        let y = *(x);
         let z = -x;
     }
 }
 "#
         .trim(),
+        "crates/ra_ide/src/snapshots/highlight_unsafe.html",
+        false,
     );
-    let dst_file = project_dir().join("crates/ra_ide/src/snapshots/highlight_unsafe.html");
-    let actual_html = &analysis.highlight_as_html(file_id, false).unwrap();
-    let expected_html = &read_text(&dst_file);
-    fs::write(dst_file, &actual_html).unwrap();
-    assert_eq_text!(expected_html, actual_html);
+}
+
+#[test]
+fn test_highlight_doctest() {
+    check_highlighting(
+        r#"
+impl Foo {
+    /// Constructs a new `Foo`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![allow(unused_mut)]
+    /// let mut foo: Foo = Foo::new();
+    /// ```
+    pub const fn new() -> Foo {
+        Foo { }
+    }
+
+    /// `bar` method on `Foo`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let foo = Foo::new();
+    ///
+    /// // calls bar on foo
+    /// assert!(foo.bar());
+    ///
+    /// /* multi-line
+    ///        comment */
+    ///
+    /// let multi_line_string = "Foo
+    ///   bar
+    ///          ";
+    ///
+    /// ```
+    ///
+    /// ```
+    /// let foobar = Foo::new().bar();
+    /// ```
+    pub fn foo(&self) -> bool {
+        true
+    }
+}
+"#
+        .trim(),
+        "crates/ra_ide/src/snapshots/highlight_doctest.html",
+        false,
+    )
 }