[wildcards] completion tests

See: #56361

Change-Id: Ib69a64b17a890c6cec0e1bddfd25f6fa7834b1cb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/378620
Commit-Queue: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

pkg/analysis_server/test/services/completion/dart/declaration/test_all.dart

@@ -23,6 +23,7 @@ import 'record_type_test.dart' as record_type;
 import 'type_member_test.dart' as type_member;
 import 'uri_test.dart' as uri;
 import 'variable_name_test.dart' as variable_name;
+import 'wildcard_variables_test.dart' as wildcard_variables;
 
 /// Tests suggestions produced for various kinds of declarations.
 void main() {
@@ -46,5 +47,6 @@ void main() {
     type_member.main();
     uri.main();
     variable_name.main();
+    wildcard_variables.main();
   });
 }

pkg/analysis_server/test/services/completion/dart/declaration/wildcard_variables_test.dart

@@ -0,0 +1,196 @@
+// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../../../../client/completion_driver_test.dart';
+
+void main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(WildcardFieldTest);
+    defineReflectiveTests(WildcardImportPrefixTest);
+    defineReflectiveTests(WildcardLocalVariableTest);
+    defineReflectiveTests(WildcardParameterTest);
+    defineReflectiveTests(WildcardTopLevelVariableTest);
+  });
+}
+
+/// Fields are binding so not technically wildcards but look just like them.
+@reflectiveTest
+class WildcardFieldTest extends AbstractCompletionDriverTest {
+  @override
+  Set<String> allowedIdentifiers = {'_'};
+
+  @override
+  bool get includeKeywords => false;
+
+  Future<void> test_argumentList() async {
+    await computeSuggestions('''
+void p(Object o) {}
+
+class C {
+  int _ = 0;
+  void f() {
+    p(^);
+  }
+''');
+    assertResponse(r'''
+suggestions
+  _
+    kind: field
+''');
+  }
+
+  @FailingTest(reason: "the local '_' is shadowing the field")
+  Future<void> test_argumentList_withLocal() async {
+    await computeSuggestions('''
+void p(Object o) {}
+
+class C {
+  int _ = 0;
+  void f() {
+    var _ = 0;
+    p(^);
+  }
+''');
+    assertResponse(r'''
+suggestions
+  _
+    kind: field
+''');
+  }
+}
+
+@reflectiveTest
+class WildcardImportPrefixTest extends AbstractCompletionDriverTest {
+  @override
+  Set<String> allowedIdentifiers = {'_', 'isBlank'};
+
+  @override
+  bool get includeKeywords => false;
+
+  @FailingTest(reason: "'_' shouldn't be suggested")
+  Future<void> test_argumentList() async {
+    newFile('$testPackageLibPath/ext.dart', '''
+extension ES on String {
+  bool get isBlank => false;
+}
+''');
+
+    await computeSuggestions('''
+import 'ext.dart' as _;
+
+void p(Object o) {}
+
+void f() {
+  p(^);
+}
+''');
+    // `_` should not appear.
+    assertResponse('''
+suggestions
+''');
+  }
+
+  Future<void> test_stringExtension_argumentList() async {
+    newFile('$testPackageLibPath/ext.dart', '''
+extension ES on String {
+  bool get isBlank => false;
+}
+''');
+
+    await computeSuggestions('''
+import 'ext.dart' as _;
+
+void p(Object o) {}
+
+void f() {
+  p(''.^);
+}
+''');
+    assertResponse('''
+suggestions
+  isBlank
+    kind: getter
+''');
+  }
+}
+
+@reflectiveTest
+class WildcardLocalVariableTest extends AbstractCompletionDriverTest {
+  @override
+  Set<String> allowedIdentifiers = {'_', 'b'};
+
+  @override
+  bool get includeKeywords => false;
+
+  @FailingTest(reason: "'_' shouldn't be suggested")
+  Future<void> test_argumentList() async {
+    await computeSuggestions('''
+void p(Object o) {}
+
+void f() {
+  var _, b = 0;
+  p(^);
+}
+''');
+    assertResponse(r'''
+  suggestions
+  b
+    kind: localVariable
+''');
+  }
+}
+
+@reflectiveTest
+class WildcardParameterTest extends AbstractCompletionDriverTest {
+  @override
+  Set<String> allowedIdentifiers = {'_', 'b'};
+
+  @override
+  bool get includeKeywords => false;
+
+  Future<void> test_argumentList() async {
+    await computeSuggestions('''
+void p(Object o) {}
+
+void f(int _, int b) {
+  p(^);
+}
+''');
+    assertResponse('''
+suggestions
+  b
+    kind: parameter
+''');
+  }
+}
+
+/// Top level variables are binding so not technically wildcards but look just
+/// like them.
+@reflectiveTest
+class WildcardTopLevelVariableTest extends AbstractCompletionDriverTest {
+  @override
+  Set<String> allowedIdentifiers = {'_'};
+
+  @override
+  bool get includeKeywords => false;
+
+  Future<void> test_argumentList() async {
+    await computeSuggestions('''
+int _ = 0;
+
+void p(Object o) {}
+
+void f() {
+  p(^);
+}
+''');
+    assertResponse(r'''
+suggestions
+  _
+    kind: topLevelVariable
+''');
+  }
+}