Merge assits::test_helpers and tests

35 files changed, 172 insertions, 180 deletions

diff --git a/crates/ra_assists/src/doc_tests.rs b/crates/ra_assists/src/doc_tests.rs
index f627f31dc..5eabb33d0 100644
--- a/crates/ra_assists/src/doc_tests.rs
+++ b/crates/ra_assists/src/doc_tests.rs
@@ -12,7 +12,7 @@ use crate::resolved_assists;
 
 fn check(assist_id: &str, before: &str, after: &str) {
     let (selection, before) = extract_range_or_offset(before);
-    let (db, file_id) = crate::helpers::with_single_file(&before);
+    let (db, file_id) = crate::tests::with_single_file(&before);
     let frange = FileRange { file_id, range: selection.into() };
 
     let assist = resolved_assists(&db, frange)
diff --git a/crates/ra_assists/src/handlers/add_custom_impl.rs b/crates/ra_assists/src/handlers/add_custom_impl.rs
index 4ea26a550..b72f7aeac 100644
--- a/crates/ra_assists/src/handlers/add_custom_impl.rs
+++ b/crates/ra_assists/src/handlers/add_custom_impl.rs
@@ -95,7 +95,7 @@ pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/add_derive.rs b/crates/ra_assists/src/handlers/add_derive.rs
index 6254eb7c4..3629dac6b 100644
--- a/crates/ra_assists/src/handlers/add_derive.rs
+++ b/crates/ra_assists/src/handlers/add_derive.rs
@@ -58,7 +58,7 @@ fn derive_insertion_offset(nominal: &ast::NominalDef) -> Option<TextSize> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::helpers::{check_assist, check_assist_target};
+    use crate::tests::{check_assist, check_assist_target};
 
     #[test]
     fn add_derive_new() {
diff --git a/crates/ra_assists/src/handlers/add_explicit_type.rs b/crates/ra_assists/src/handlers/add_explicit_type.rs
index bc313782b..e39e1f4f3 100644
--- a/crates/ra_assists/src/handlers/add_explicit_type.rs
+++ b/crates/ra_assists/src/handlers/add_explicit_type.rs
@@ -77,7 +77,7 @@ pub(crate) fn add_explicit_type(ctx: AssistCtx) -> Option<Assist> {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn add_explicit_type_target() {
diff --git a/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs b/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
index 49deb6701..ee0d5ce98 100644
--- a/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
+++ b/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
@@ -97,7 +97,7 @@ fn existing_from_impl(
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
     use test_utils::covers;
 
     #[test]
diff --git a/crates/ra_assists/src/handlers/add_function.rs b/crates/ra_assists/src/handlers/add_function.rs
index 6c7456579..cb2afc863 100644
--- a/crates/ra_assists/src/handlers/add_function.rs
+++ b/crates/ra_assists/src/handlers/add_function.rs
@@ -283,7 +283,7 @@ fn next_space_for_fn_in_module(
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/add_impl.rs b/crates/ra_assists/src/handlers/add_impl.rs
index d26f8b93d..3d390c20b 100644
--- a/crates/ra_assists/src/handlers/add_impl.rs
+++ b/crates/ra_assists/src/handlers/add_impl.rs
@@ -60,7 +60,7 @@ pub(crate) fn add_impl(ctx: AssistCtx) -> Option<Assist> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::helpers::{check_assist, check_assist_target};
+    use crate::tests::{check_assist, check_assist_target};
 
     #[test]
     fn test_add_impl() {
diff --git a/crates/ra_assists/src/handlers/add_missing_impl_members.rs b/crates/ra_assists/src/handlers/add_missing_impl_members.rs
index e47feda71..f7a101503 100644
--- a/crates/ra_assists/src/handlers/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/handlers/add_missing_impl_members.rs
@@ -181,7 +181,7 @@ fn add_body(fn_def: ast::FnDef) -> ast::FnDef {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/add_new.rs b/crates/ra_assists/src/handlers/add_new.rs
index e8a36c7de..1b5d604d1 100644
--- a/crates/ra_assists/src/handlers/add_new.rs
+++ b/crates/ra_assists/src/handlers/add_new.rs
@@ -178,7 +178,7 @@ fn has_new_fn(imp: &ast::ImplDef) -> bool {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/apply_demorgan.rs b/crates/ra_assists/src/handlers/apply_demorgan.rs
index 260b9e073..a0c48d872 100644
--- a/crates/ra_assists/src/handlers/apply_demorgan.rs
+++ b/crates/ra_assists/src/handlers/apply_demorgan.rs
@@ -60,7 +60,7 @@ fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     #[test]
     fn demorgan_turns_and_into_or() {
diff --git a/crates/ra_assists/src/handlers/auto_import.rs b/crates/ra_assists/src/handlers/auto_import.rs
index db6c4d2fa..9e4171ccd 100644
--- a/crates/ra_assists/src/handlers/auto_import.rs
+++ b/crates/ra_assists/src/handlers/auto_import.rs
@@ -277,7 +277,7 @@ impl ImportCandidate {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn applicable_when_found_an_import() {
diff --git a/crates/ra_assists/src/handlers/change_visibility.rs b/crates/ra_assists/src/handlers/change_visibility.rs
index 1cd532e80..6ac1f8e69 100644
--- a/crates/ra_assists/src/handlers/change_visibility.rs
+++ b/crates/ra_assists/src/handlers/change_visibility.rs
@@ -110,7 +110,7 @@ fn change_vis(ctx: AssistCtx, vis: ast::Visibility) -> Option<Assist> {
 mod tests {
     use test_utils::covers;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/early_return.rs b/crates/ra_assists/src/handlers/early_return.rs
index eede2fe91..55ccc37b0 100644
--- a/crates/ra_assists/src/handlers/early_return.rs
+++ b/crates/ra_assists/src/handlers/early_return.rs
@@ -182,7 +182,7 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx) -> Option<Assist> {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/fill_match_arms.rs b/crates/ra_assists/src/handlers/fill_match_arms.rs
index 8d1af9933..1f9cd5585 100644
--- a/crates/ra_assists/src/handlers/fill_match_arms.rs
+++ b/crates/ra_assists/src/handlers/fill_match_arms.rs
@@ -168,7 +168,7 @@ fn build_pat(db: &RootDatabase, module: hir::Module, var: hir::EnumVariant) -> O
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     use super::fill_match_arms;
 
diff --git a/crates/ra_assists/src/handlers/flip_binexpr.rs b/crates/ra_assists/src/handlers/flip_binexpr.rs
index 8030efb35..41db963dc 100644
--- a/crates/ra_assists/src/handlers/flip_binexpr.rs
+++ b/crates/ra_assists/src/handlers/flip_binexpr.rs
@@ -69,7 +69,7 @@ impl From<BinOp> for FlipAction {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn flip_binexpr_target_is_the_op() {
diff --git a/crates/ra_assists/src/handlers/flip_comma.rs b/crates/ra_assists/src/handlers/flip_comma.rs
index 1dacf29f8..e65c9a41d 100644
--- a/crates/ra_assists/src/handlers/flip_comma.rs
+++ b/crates/ra_assists/src/handlers/flip_comma.rs
@@ -39,7 +39,7 @@ pub(crate) fn flip_comma(ctx: AssistCtx) -> Option<Assist> {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_target};
+    use crate::tests::{check_assist, check_assist_target};
 
     #[test]
     fn flip_comma_works_for_function_parameters() {
diff --git a/crates/ra_assists/src/handlers/flip_trait_bound.rs b/crates/ra_assists/src/handlers/flip_trait_bound.rs
index f56769624..f186da585 100644
--- a/crates/ra_assists/src/handlers/flip_trait_bound.rs
+++ b/crates/ra_assists/src/handlers/flip_trait_bound.rs
@@ -43,7 +43,7 @@ pub(crate) fn flip_trait_bound(ctx: AssistCtx) -> Option<Assist> {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn flip_trait_bound_assist_available() {
diff --git a/crates/ra_assists/src/handlers/inline_local_variable.rs b/crates/ra_assists/src/handlers/inline_local_variable.rs
index 60ec536a7..5f3b8dfd1 100644
--- a/crates/ra_assists/src/handlers/inline_local_variable.rs
+++ b/crates/ra_assists/src/handlers/inline_local_variable.rs
@@ -125,7 +125,7 @@ pub(crate) fn inline_local_variable(ctx: AssistCtx) -> Option<Assist> {
 mod tests {
     use test_utils::covers;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/introduce_variable.rs b/crates/ra_assists/src/handlers/introduce_variable.rs
index 39c656305..9c2c20b22 100644
--- a/crates/ra_assists/src/handlers/introduce_variable.rs
+++ b/crates/ra_assists/src/handlers/introduce_variable.rs
@@ -136,7 +136,7 @@ fn anchor_stmt(expr: ast::Expr) -> Option<(SyntaxNode, bool)> {
 mod tests {
     use test_utils::covers;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/invert_if.rs b/crates/ra_assists/src/handlers/invert_if.rs
index 682e08512..303c1806d 100644
--- a/crates/ra_assists/src/handlers/invert_if.rs
+++ b/crates/ra_assists/src/handlers/invert_if.rs
@@ -62,7 +62,7 @@ pub(crate) fn invert_if(ctx: AssistCtx) -> Option<Assist> {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     #[test]
     fn invert_if_remove_inequality() {
diff --git a/crates/ra_assists/src/handlers/merge_imports.rs b/crates/ra_assists/src/handlers/merge_imports.rs
index 4be1238f1..9a2083609 100644
--- a/crates/ra_assists/src/handlers/merge_imports.rs
+++ b/crates/ra_assists/src/handlers/merge_imports.rs
@@ -125,7 +125,7 @@ fn first_path(path: &ast::Path) -> ast::Path {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::check_assist;
+    use crate::tests::check_assist;
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/merge_match_arms.rs b/crates/ra_assists/src/handlers/merge_match_arms.rs
index 5a77d3dbc..9ae099b41 100644
--- a/crates/ra_assists/src/handlers/merge_match_arms.rs
+++ b/crates/ra_assists/src/handlers/merge_match_arms.rs
@@ -105,7 +105,7 @@ fn contains_placeholder(a: &ast::MatchArm) -> bool {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/move_bounds.rs b/crates/ra_assists/src/handlers/move_bounds.rs
index 0f26884dc..89956aea9 100644
--- a/crates/ra_assists/src/handlers/move_bounds.rs
+++ b/crates/ra_assists/src/handlers/move_bounds.rs
@@ -89,7 +89,7 @@ fn build_predicate(param: ast::TypeParam) -> Option<ast::WherePred> {
 mod tests {
     use super::*;
 
-    use crate::helpers::check_assist;
+    use crate::tests::check_assist;
 
     #[test]
     fn move_bounds_to_where_clause_fn() {
diff --git a/crates/ra_assists/src/handlers/move_guard.rs b/crates/ra_assists/src/handlers/move_guard.rs
index b084dd9ee..f2aa7e594 100644
--- a/crates/ra_assists/src/handlers/move_guard.rs
+++ b/crates/ra_assists/src/handlers/move_guard.rs
@@ -132,7 +132,7 @@ pub(crate) fn move_arm_cond_to_match_guard(ctx: AssistCtx) -> Option<Assist> {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn move_guard_to_arm_body_target() {
diff --git a/crates/ra_assists/src/handlers/raw_string.rs b/crates/ra_assists/src/handlers/raw_string.rs
index 567400b9c..542f7a637 100644
--- a/crates/ra_assists/src/handlers/raw_string.rs
+++ b/crates/ra_assists/src/handlers/raw_string.rs
@@ -138,7 +138,7 @@ fn count_hashes(s: &str) -> usize {
 #[cfg(test)]
 mod test {
     use super::*;
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn make_raw_string_target() {
diff --git a/crates/ra_assists/src/handlers/remove_dbg.rs b/crates/ra_assists/src/handlers/remove_dbg.rs
index 4e5eb4350..ddfb21a7e 100644
--- a/crates/ra_assists/src/handlers/remove_dbg.rs
+++ b/crates/ra_assists/src/handlers/remove_dbg.rs
@@ -90,7 +90,7 @@ fn is_valid_macrocall(macro_call: &ast::MacroCall, macro_name: &str) -> Option<b
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn test_remove_dbg() {
diff --git a/crates/ra_assists/src/handlers/reorder_fields.rs b/crates/ra_assists/src/handlers/reorder_fields.rs
index 5cbb98d73..a57e327b8 100644
--- a/crates/ra_assists/src/handlers/reorder_fields.rs
+++ b/crates/ra_assists/src/handlers/reorder_fields.rs
@@ -109,7 +109,7 @@ fn compute_fields_ranks(path: &Path, ctx: &AssistCtx) -> Option<HashMap<String,
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
index 9841f6980..d0df3b84e 100644
--- a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
@@ -74,7 +74,7 @@ pub(crate) fn replace_if_let_with_match(ctx: AssistCtx) -> Option<Assist> {
 mod tests {
     use super::*;
 
-    use crate::helpers::{check_assist, check_assist_target};
+    use crate::tests::{check_assist, check_assist_target};
 
     #[test]
     fn test_replace_if_let_with_match_unwraps_simple_expressions() {
diff --git a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
index 0cf23b754..dc4d16055 100644
--- a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
+++ b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
@@ -74,7 +74,7 @@ pub(crate) fn replace_let_with_if_let(ctx: AssistCtx) -> Option<Assist> {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::check_assist;
+    use crate::tests::check_assist;
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
index ff2463c77..624178924 100644
--- a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
@@ -74,7 +74,7 @@ fn collect_hir_path_segments(path: &hir::Path) -> Option<Vec<SmolStr>> {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
index 62d4ea522..dcb471edb 100644
--- a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
@@ -63,7 +63,7 @@ pub(crate) fn replace_unwrap_with_match(ctx: AssistCtx) -> Option<Assist> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::helpers::{check_assist, check_assist_target};
+    use crate::tests::{check_assist, check_assist_target};
 
     #[test]
     fn test_replace_result_unwrap_with_match() {
diff --git a/crates/ra_assists/src/handlers/split_import.rs b/crates/ra_assists/src/handlers/split_import.rs
index f25826796..a59f2f76f 100644
--- a/crates/ra_assists/src/handlers/split_import.rs
+++ b/crates/ra_assists/src/handlers/split_import.rs
@@ -37,7 +37,7 @@ pub(crate) fn split_import(ctx: AssistCtx) -> Option<Assist> {
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/handlers/unwrap_block.rs b/crates/ra_assists/src/handlers/unwrap_block.rs
index 859c70ad8..89992117d 100644
--- a/crates/ra_assists/src/handlers/unwrap_block.rs
+++ b/crates/ra_assists/src/handlers/unwrap_block.rs
@@ -89,7 +89,7 @@ fn extract_expr(cursor_range: TextRange, block: ast::BlockExpr) -> Option<ast::E
 
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 0f94f5ee8..b84d60c77 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -14,6 +14,8 @@ mod assist_ctx;
 mod marks;
 #[cfg(test)]
 mod doc_tests;
+#[cfg(test)]
+mod tests;
 pub mod utils;
 pub mod ast_transform;
 
@@ -194,150 +196,3 @@ mod handlers {
         ]
     }
 }
-
-#[cfg(test)]
-mod helpers {
-    use std::sync::Arc;
-
-    use hir::Semantics;
-    use ra_db::{fixture::WithFixture, FileId, FileRange, SourceDatabaseExt};
-    use ra_ide_db::{symbol_index::SymbolsDatabase, RootDatabase};
-    use test_utils::{add_cursor, assert_eq_text, extract_range_or_offset, RangeOrOffset};
-
-    use crate::{handlers::Handler, AssistCtx, AssistFile};
-
-    pub(crate) fn with_single_file(text: &str) -> (RootDatabase, FileId) {
-        let (mut db, file_id) = RootDatabase::with_single_file(text);
-        // FIXME: ideally, this should be done by the above `RootDatabase::with_single_file`,
-        // but it looks like this might need specialization? :(
-        db.set_local_roots(Arc::new(vec![db.file_source_root(file_id)]));
-        (db, file_id)
-    }
-
-    pub(crate) fn check_assist(assist: Handler, ra_fixture_before: &str, ra_fixture_after: &str) {
-        check(assist, ra_fixture_before, ExpectedResult::After(ra_fixture_after));
-    }
-
-    // FIXME: instead of having a separate function here, maybe use
-    // `extract_ranges` and mark the target as `<target> </target>` in the
-    // fixuture?
-    pub(crate) fn check_assist_target(assist: Handler, ra_fixture: &str, target: &str) {
-        check(assist, ra_fixture, ExpectedResult::Target(target));
-    }
-
-    pub(crate) fn check_assist_not_applicable(assist: Handler, ra_fixture: &str) {
-        check(assist, ra_fixture, ExpectedResult::NotApplicable);
-    }
-
-    enum ExpectedResult<'a> {
-        NotApplicable,
-        After(&'a str),
-        Target(&'a str),
-    }
-
-    fn check(assist: Handler, before: &str, expected: ExpectedResult) {
-        let (text_without_caret, file_with_caret_id, range_or_offset, db) =
-            if before.contains("//-") {
-                let (mut db, position) = RootDatabase::with_position(before);
-                db.set_local_roots(Arc::new(vec![db.file_source_root(position.file_id)]));
-                (
-                    db.file_text(position.file_id).as_ref().to_owned(),
-                    position.file_id,
-                    RangeOrOffset::Offset(position.offset),
-                    db,
-                )
-            } else {
-                let (range_or_offset, text_without_caret) = extract_range_or_offset(before);
-                let (db, file_id) = with_single_file(&text_without_caret);
-                (text_without_caret, file_id, range_or_offset, db)
-            };
-
-        let frange = FileRange { file_id: file_with_caret_id, range: range_or_offset.into() };
-
-        let sema = Semantics::new(&db);
-        let assist_ctx = AssistCtx::new(&sema, frange, true);
-
-        match (assist(assist_ctx), expected) {
-            (Some(assist), ExpectedResult::After(after)) => {
-                let action = assist.0[0].action.clone().unwrap();
-
-                let mut actual = if let AssistFile::TargetFile(file_id) = action.file {
-                    db.file_text(file_id).as_ref().to_owned()
-                } else {
-                    text_without_caret
-                };
-                action.edit.apply(&mut actual);
-
-                match action.cursor_position {
-                    None => {
-                        if let RangeOrOffset::Offset(before_cursor_pos) = range_or_offset {
-                            let off = action
-                                .edit
-                                .apply_to_offset(before_cursor_pos)
-                                .expect("cursor position is affected by the edit");
-                            actual = add_cursor(&actual, off)
-                        }
-                    }
-                    Some(off) => actual = add_cursor(&actual, off),
-                };
-
-                assert_eq_text!(after, &actual);
-            }
-            (Some(assist), ExpectedResult::Target(target)) => {
-                let action = assist.0[0].action.clone().unwrap();
-                let range = action.target.expect("expected target on action");
-                assert_eq_text!(&text_without_caret[range], target);
-            }
-            (Some(_), ExpectedResult::NotApplicable) => panic!("assist should not be applicable!"),
-            (None, ExpectedResult::After(_)) | (None, ExpectedResult::Target(_)) => {
-                panic!("code action is not applicable")
-            }
-            (None, ExpectedResult::NotApplicable) => (),
-        };
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use ra_db::FileRange;
-    use ra_syntax::TextRange;
-    use test_utils::{extract_offset, extract_range};
-
-    use crate::{helpers, resolved_assists};
-
-    #[test]
-    fn assist_order_field_struct() {
-        let before = "struct Foo { <|>bar: u32 }";
-        let (before_cursor_pos, before) = extract_offset(before);
-        let (db, file_id) = helpers::with_single_file(&before);
-        let frange = FileRange { file_id, range: TextRange::empty(before_cursor_pos) };
-        let assists = resolved_assists(&db, frange);
-        let mut assists = assists.iter();
-
-        assert_eq!(
-            assists.next().expect("expected assist").label.label,
-            "Change visibility to pub(crate)"
-        );
-        assert_eq!(assists.next().expect("expected assist").label.label, "Add `#[derive]`");
-    }
-
-    #[test]
-    fn assist_order_if_expr() {
-        let before = "
-        pub fn test_some_range(a: int) -> bool {
-            if let 2..6 = <|>5<|> {
-                true
-            } else {
-                false
-            }
-        }";
-        let (range, before) = extract_range(before);
-        let (db, file_id) = helpers::with_single_file(&before);
-        let frange = FileRange { file_id, range };
-        let assists = resolved_assists(&db, frange);
-        let mut assists = assists.iter();
-
-        assert_eq!(assists.next().expect("expected assist").label.label, "Extract into variable");
-        assert_eq!(assists.next().expect("expected assist").label.label, "Replace with match");
-    }
-}
diff --git a/crates/ra_assists/src/tests.rs b/crates/ra_assists/src/tests.rs
new file mode 100644
index 000000000..ca3096a43
--- /dev/null
+++ b/crates/ra_assists/src/tests.rs
@@ -0,0 +1,137 @@
+use std::sync::Arc;
+
+use hir::Semantics;
+use ra_db::{fixture::WithFixture, FileId, FileRange, SourceDatabaseExt};
+use ra_ide_db::{symbol_index::SymbolsDatabase, RootDatabase};
+use ra_syntax::TextRange;
+use test_utils::{
+    add_cursor, assert_eq_text, extract_offset, extract_range, extract_range_or_offset,
+    RangeOrOffset,
+};
+
+use crate::{handlers::Handler, resolved_assists, AssistCtx, AssistFile};
+
+pub(crate) fn with_single_file(text: &str) -> (RootDatabase, FileId) {
+    let (mut db, file_id) = RootDatabase::with_single_file(text);
+    // FIXME: ideally, this should be done by the above `RootDatabase::with_single_file`,
+    // but it looks like this might need specialization? :(
+    db.set_local_roots(Arc::new(vec![db.file_source_root(file_id)]));
+    (db, file_id)
+}
+
+pub(crate) fn check_assist(assist: Handler, ra_fixture_before: &str, ra_fixture_after: &str) {
+    check(assist, ra_fixture_before, ExpectedResult::After(ra_fixture_after));
+}
+
+// FIXME: instead of having a separate function here, maybe use
+// `extract_ranges` and mark the target as `<target> </target>` in the
+// fixuture?
+pub(crate) fn check_assist_target(assist: Handler, ra_fixture: &str, target: &str) {
+    check(assist, ra_fixture, ExpectedResult::Target(target));
+}
+
+pub(crate) fn check_assist_not_applicable(assist: Handler, ra_fixture: &str) {
+    check(assist, ra_fixture, ExpectedResult::NotApplicable);
+}
+
+enum ExpectedResult<'a> {
+    NotApplicable,
+    After(&'a str),
+    Target(&'a str),
+}
+
+fn check(assist: Handler, before: &str, expected: ExpectedResult) {
+    let (text_without_caret, file_with_caret_id, range_or_offset, db) = if before.contains("//-") {
+        let (mut db, position) = RootDatabase::with_position(before);
+        db.set_local_roots(Arc::new(vec![db.file_source_root(position.file_id)]));
+        (
+            db.file_text(position.file_id).as_ref().to_owned(),
+            position.file_id,
+            RangeOrOffset::Offset(position.offset),
+            db,
+        )
+    } else {
+        let (range_or_offset, text_without_caret) = extract_range_or_offset(before);
+        let (db, file_id) = with_single_file(&text_without_caret);
+        (text_without_caret, file_id, range_or_offset, db)
+    };
+
+    let frange = FileRange { file_id: file_with_caret_id, range: range_or_offset.into() };
+
+    let sema = Semantics::new(&db);
+    let assist_ctx = AssistCtx::new(&sema, frange, true);
+
+    match (assist(assist_ctx), expected) {
+        (Some(assist), ExpectedResult::After(after)) => {
+            let action = assist.0[0].action.clone().unwrap();
+
+            let mut actual = if let AssistFile::TargetFile(file_id) = action.file {
+                db.file_text(file_id).as_ref().to_owned()
+            } else {
+                text_without_caret
+            };
+            action.edit.apply(&mut actual);
+
+            match action.cursor_position {
+                None => {
+                    if let RangeOrOffset::Offset(before_cursor_pos) = range_or_offset {
+                        let off = action
+                            .edit
+                            .apply_to_offset(before_cursor_pos)
+                            .expect("cursor position is affected by the edit");
+                        actual = add_cursor(&actual, off)
+                    }
+                }
+                Some(off) => actual = add_cursor(&actual, off),
+            };
+
+            assert_eq_text!(after, &actual);
+        }
+        (Some(assist), ExpectedResult::Target(target)) => {
+            let action = assist.0[0].action.clone().unwrap();
+            let range = action.target.expect("expected target on action");
+            assert_eq_text!(&text_without_caret[range], target);
+        }
+        (Some(_), ExpectedResult::NotApplicable) => panic!("assist should not be applicable!"),
+        (None, ExpectedResult::After(_)) | (None, ExpectedResult::Target(_)) => {
+            panic!("code action is not applicable")
+        }
+        (None, ExpectedResult::NotApplicable) => (),
+    };
+}
+
+#[test]
+fn assist_order_field_struct() {
+    let before = "struct Foo { <|>bar: u32 }";
+    let (before_cursor_pos, before) = extract_offset(before);
+    let (db, file_id) = with_single_file(&before);
+    let frange = FileRange { file_id, range: TextRange::empty(before_cursor_pos) };
+    let assists = resolved_assists(&db, frange);
+    let mut assists = assists.iter();
+
+    assert_eq!(
+        assists.next().expect("expected assist").label.label,
+        "Change visibility to pub(crate)"
+    );
+    assert_eq!(assists.next().expect("expected assist").label.label, "Add `#[derive]`");
+}
+
+#[test]
+fn assist_order_if_expr() {
+    let before = "
+    pub fn test_some_range(a: int) -> bool {
+        if let 2..6 = <|>5<|> {
+            true
+        } else {
+            false
+        }
+    }";
+    let (range, before) = extract_range(before);
+    let (db, file_id) = with_single_file(&before);
+    let frange = FileRange { file_id, range };
+    let assists = resolved_assists(&db, frange);
+    let mut assists = assists.iter();
+
+    assert_eq!(assists.next().expect("expected assist").label.label, "Extract into variable");
+    assert_eq!(assists.next().expect("expected assist").label.label, "Replace with match");
+}