Fix remove_type_annotation fix/assist to work with for loops (issue 39628)

Change-Id: Ie212ea369cb2c0d4d8b37b50928d3935fad6a445
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127101
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

Author: bwilkerson

pkg/analysis_server/lib/src/services/correction/base_processor.dart

@@ -1094,8 +1094,28 @@ abstract class BaseProcessor {
     VariableDeclarationList declarationList =
         node.thisOrAncestorOfType<VariableDeclarationList>();
     if (declarationList == null) {
-      _coverageMarker();
-      return null;
+      DeclaredIdentifier declaration = node.thisOrAncestorOfType();
+      if (declaration == null) {
+        _coverageMarker();
+        return null;
+      }
+      TypeAnnotation typeNode = declaration.type;
+      if (typeNode == null) {
+        _coverageMarker();
+        return null;
+      }
+      Token keyword = declaration.keyword;
+      var variableName = declaration.identifier;
+      var changeBuilder = _newDartChangeBuilder();
+      await changeBuilder.addFileEdit(file, (DartFileEditBuilder builder) {
+        SourceRange typeRange = range.startStart(typeNode, variableName);
+        if (keyword != null && keyword.lexeme != 'var') {
+          builder.addSimpleReplacement(typeRange, '');
+        } else {
+          builder.addSimpleReplacement(typeRange, 'var ');
+        }
+      });
+      return changeBuilder;
     }
     // we need a type
     TypeAnnotation typeNode = declarationList.type;

pkg/analysis_server/test/src/services/correction/assist/remove_type_annotation_test.dart

@@ -54,24 +54,6 @@ class A {
     await assertNoAssistAt('v;');
   }
 
-  test_localVariable_noInitializer() async {
-    await resolveTestUnit('''
-main() {
-  int v;
-}
-''');
-    await assertNoAssistAt('v;');
-  }
-
-  test_localVariable_onInitializer() async {
-    await resolveTestUnit('''
-main() {
-  final int v = 1;
-}
-''');
-    await assertNoAssistAt('1;');
-  }
-
   test_localVariable() async {
     await resolveTestUnit('''
 main() {
@@ -111,20 +93,44 @@ main() {
 ''');
   }
 
-  test_topLevelVariable_noInitializer() async {
-    verifyNoTestUnitErrors = false;
+  test_localVariable_noInitializer() async {
     await resolveTestUnit('''
-int v;
+main() {
+  int v;
+}
 ''');
     await assertNoAssistAt('v;');
   }
 
-  test_topLevelVariable_syntheticName() async {
-    verifyNoTestUnitErrors = false;
+  test_localVariable_onInitializer() async {
     await resolveTestUnit('''
-MyType
+main() {
+  final int v = 1;
+}
 ''');
-    await assertNoAssistAt('MyType');
+    await assertNoAssistAt('1;');
+  }
+
+  test_loopVariable() async {
+    await resolveTestUnit('''
+main() {
+  for(int i = 0; i < 3; i++) {}
+}
+''');
+    await assertHasAssistAt('int ', '''
+main() {
+  for(var i = 0; i < 3; i++) {}
+}
+''');
+  }
+
+  test_loopVariable_noType() async {
+    await resolveTestUnit('''
+main() {
+  for(var i = 0; i < 3; i++) {}
+}
+''');
+    await assertNoAssistAt('var ');
   }
 
   test_topLevelVariable() async {
@@ -144,4 +150,20 @@ final int V = 1;
 final V = 1;
 ''');
   }
+
+  test_topLevelVariable_noInitializer() async {
+    verifyNoTestUnitErrors = false;
+    await resolveTestUnit('''
+int v;
+''');
+    await assertNoAssistAt('v;');
+  }
+
+  test_topLevelVariable_syntheticName() async {
+    verifyNoTestUnitErrors = false;
+    await resolveTestUnit('''
+MyType
+''');
+    await assertNoAssistAt('MyType');
+  }
 }