[analysis_server] Dot shorthands: Document highlights tests.

Tests for documenting highlighting for dot shorthands. Tested with enums, classes, and extension types.

Bug: #59836
Change-Id: I9b13dd8594ff8113ec9dbe97089688d893d2853d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/431983
Commit-Queue: Kallen Tu <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: kallentu

pkg/analysis_server/test/lsp/document_highlights_test.dart

@@ -64,6 +64,43 @@ var a; // Not a reference
       _testMarkedContent('''
 var /*[0*/^a/*0]*/ = [''].where((_) => true).toList();
 var b = /*[1*/a/*1]*/;
+''');
+
+  Future<void> test_dotShorthand_class() => _testMarkedContent('''
+A topA = ./*[0*/^a/*0]*/;
+class A {
+  static A get /*[1*/a/*1]*/ => A();
+}
+void fn(A a) => print(a);
+void f() {
+  A a = ./*[2*/a/*2]*/;
+  fn(./*[3*/a/*3]*/);
+  A aa = A./*[4*/a/*4]*/;
+}
+''');
+
+  Future<void> test_dotShorthand_enum() => _testMarkedContent('''
+const A constA = ./*[0*/^a/*0]*/;
+enum A { /*[1*/a/*1]*/ }
+void fn(A a) => print(a);
+void f() {
+  A a = ./*[2*/a/*2]*/;
+  fn(./*[3*/a/*3]*/);
+  A aa = A./*[4*/a/*4]*/;
+}
+''');
+
+  Future<void> test_dotShorthand_extensionType() => _testMarkedContent('''
+A topA = ./*[0*/^a/*0]*/;
+extension type A(int x) {
+  static A get /*[1*/a/*1]*/ => A(1);
+}
+void fn(A a) => print(a);
+void f() {
+  A a = ./*[2*/a/*2]*/;
+  fn(./*[3*/a/*3]*/);
+  A aa = A./*[4*/a/*4]*/;
+}
 ''');
 
   Future<void> test_forInLoop() => _testMarkedContent('''