1 files changed, 144 insertions, 0 deletions

diff --git a/crates/ide_db/src/traits/tests.rs b/crates/ide_db/src/traits/tests.rs
new file mode 100644
index 000000000..09c7ac3ec
--- /dev/null
+++ b/crates/ide_db/src/traits/tests.rs
@@ -0,0 +1,144 @@
+use crate::RootDatabase;
+use base_db::{fixture::ChangeFixture, FilePosition};
+use expect_test::{expect, Expect};
+use hir::Semantics;
+use syntax::ast::{self, AstNode};
+use test_utils::RangeOrOffset;
+
+/// Creates analysis from a multi-file fixture, returns positions marked with <|>.
+pub(crate) fn position(ra_fixture: &str) -> (RootDatabase, FilePosition) {
+    let change_fixture = ChangeFixture::parse(ra_fixture);
+    let mut database = RootDatabase::default();
+    database.apply_change(change_fixture.change);
+    let (file_id, range_or_offset) = change_fixture.file_position.expect("expected a marker (<|>)");
+    let offset = match range_or_offset {
+        RangeOrOffset::Range(_) => panic!(),
+        RangeOrOffset::Offset(it) => it,
+    };
+    (database, FilePosition { file_id, offset })
+}
+
+fn check_trait(ra_fixture: &str, expect: Expect) {
+    let (db, position) = position(ra_fixture);
+    let sema = Semantics::new(&db);
+    let file = sema.parse(position.file_id);
+    let impl_block: ast::Impl =
+        sema.find_node_at_offset_with_descend(file.syntax(), position.offset).unwrap();
+    let trait_ = crate::traits::resolve_target_trait(&sema, &impl_block);
+    let actual = match trait_ {
+        Some(trait_) => trait_.name(&db).to_string(),
+        None => String::new(),
+    };
+    expect.assert_eq(&actual);
+}
+
+fn check_missing_assoc(ra_fixture: &str, expect: Expect) {
+    let (db, position) = position(ra_fixture);
+    let sema = Semantics::new(&db);
+    let file = sema.parse(position.file_id);
+    let impl_block: ast::Impl =
+        sema.find_node_at_offset_with_descend(file.syntax(), position.offset).unwrap();
+    let items = crate::traits::get_missing_assoc_items(&sema, &impl_block);
+    let actual = items
+        .into_iter()
+        .map(|item| item.name(&db).unwrap().to_string())
+        .collect::<Vec<_>>()
+        .join("\n");
+    expect.assert_eq(&actual);
+}
+
+#[test]
+fn resolve_trait() {
+    check_trait(
+        r#"
+pub trait Foo {
+    fn bar();
+}
+impl Foo for u8 {
+    <|>
+}
+            "#,
+        expect![["Foo"]],
+    );
+    check_trait(
+        r#"
+pub trait Foo {
+    fn bar();
+}
+impl Foo for u8 {
+    fn bar() {
+        fn baz() {
+            <|>
+        }
+        baz();
+    }
+}
+            "#,
+        expect![["Foo"]],
+    );
+    check_trait(
+        r#"
+pub trait Foo {
+    fn bar();
+}
+pub struct Bar;
+impl Bar {
+    <|>
+}
+            "#,
+        expect![[""]],
+    );
+}
+
+#[test]
+fn missing_assoc_items() {
+    check_missing_assoc(
+        r#"
+pub trait Foo {
+    const FOO: u8;
+    fn bar();
+}
+impl Foo for u8 {
+    <|>
+}"#,
+        expect![[r#"
+                FOO
+                bar"#]],
+    );
+
+    check_missing_assoc(
+        r#"
+pub trait Foo {
+    const FOO: u8;
+    fn bar();
+}
+impl Foo for u8 {
+    const FOO: u8 = 10;
+    <|>
+}"#,
+        expect![[r#"
+                bar"#]],
+    );
+
+    check_missing_assoc(
+        r#"
+pub trait Foo {
+    const FOO: u8;
+    fn bar();
+}
+impl Foo for u8 {
+    const FOO: u8 = 10;
+    fn bar() {<|>}
+}"#,
+        expect![[r#""#]],
+    );
+
+    check_missing_assoc(
+        r#"
+pub struct Foo;
+impl Foo {
+    fn bar() {<|>}
+}"#,
+        expect![[r#""#]],
+    );
+}