Issue 25095. Add 'Change X to Y type annotation' Quick Fix.

pkg/analysis_server/test/services/correction/fix_test.dart

Index: pkg/analysis_server/test/services/correction/fix_test.dart
diff --git a/pkg/analysis_server/test/services/correction/fix_test.dart b/pkg/analysis_server/test/services/correction/fix_test.dart
index a54eb0085168550511eccd2fab76a53f3c558375..6f0d8ab05171ee679a2d7586811c9f608d1a3e26 100644
--- a/pkg/analysis_server/test/services/correction/fix_test.dart
+++ b/pkg/analysis_server/test/services/correction/fix_test.dart
@@ -597,6 +597,55 @@ main(B b) {
 ''');
   }
 
+  test_changeTypeAnnotation_BAD_multipleVariables() async {
+    resolveTestUnit('''
+main() {
+  String a, b = 42;
+}
+''');
+    await assertNoFix(DartFixKind.CHANGE_TYPE_ANNOTATION);
+  }
+
+  test_changeTypeAnnotation_BAD_notVariableDeclaration() async {
+    resolveTestUnit('''
+main() {
+  String p;
+  p = 42;
+}
+''');
+    await assertNoFix(DartFixKind.CHANGE_TYPE_ANNOTATION);
+  }
+
+  test_changeTypeAnnotation_OK_generic() async {
+    resolveTestUnit('''
+main() {
+  String v = <int>[];
+}
+''');
+    await assertHasFix(
+        DartFixKind.CHANGE_TYPE_ANNOTATION,
+        '''
+main() {
+  List<int> v = <int>[];
+}
+''');
+  }
+
+  test_changeTypeAnnotation_OK_simple() async {
+    resolveTestUnit('''
+main() {
+  String v = 'abc'.length;
+}
+''');
+    await assertHasFix(
+        DartFixKind.CHANGE_TYPE_ANNOTATION,
+        '''
+main() {
+  int v = 'abc'.length;
+}
+''');
+  }
+
   test_createClass() async {
     resolveTestUnit('''
 main() {