use_build_context_synchronously: handle asynchrony in for- and do-sta…

…tements better (dart-lang/linter#4554)
dart-lang · Jul 12, 2023 · 3637663 · 3637663
1 parent e71d5cc
commit 3637663
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Showing 3 changed files with 142 additions and 22 deletions.
diff --git a/lib/src/rules/use_build_context_synchronously.dart b/lib/src/rules/use_build_context_synchronously.dart
@@ -722,13 +722,15 @@ class AsyncStateVisitor extends SimpleAstVisitor<AsyncState> {
   /// Compute the [AsyncState] of a "block-like" node which has [statements].
   AsyncState? _visitBlockLike(List<Statement> statements,
       {required AstNode? parent}) {
+    var reference = this.reference;
     if (reference is Statement) {
-      var index = statements.indexOf(reference as Statement);
+      var index = statements.indexOf(reference);
       if (index >= 0) {
         var precedingAsyncState = _inOrderAsyncStateGuardable(statements);
         if (precedingAsyncState != null) return precedingAsyncState;
-        // TODO(srawlins): Also DoStatement and ForStatement.
-        if (parent is WhileStatement) {
+        if (parent is DoStatement ||
+            parent is ForStatement ||
+            parent is WhileStatement) {
           // Check for asynchrony in the statements that _follow_ [reference],
           // as they may lead to an async gap before we loop back to
           // [reference].

diff --git a/test/rules/use_build_context_synchronously_test.dart b/test/rules/use_build_context_synchronously_test.dart
@@ -204,6 +204,36 @@ void foo(BuildContext context) async {
     expect(conditional.asyncStateFor(reference), isNull);
   }
 
+  test_doWhileStatement_referenceInBody_asyncInBody() async {
+    await resolveCode(r'''
+import 'package:flutter/widgets.dart';
+void foo(BuildContext context) async {
+  do {
+    await Future.value();
+    context /* ref */;
+  } while (true);
+}
+''');
+    var block = findNode.block('context /* ref */');
+    var reference = findNode.statement('context /* ref */');
+    expect(block.asyncStateFor(reference), AsyncState.asynchronous);
+  }
+
+  test_doWhileStatement_referenceInBody_asyncInBody2() async {
+    await resolveCode(r'''
+import 'package:flutter/widgets.dart';
+void foo(BuildContext context) async {
+  do {
+    context /* ref */;
+    await Future.value();
+  } while (true);
+}
+''');
+    var block = findNode.block('context /* ref */');
+    var reference = findNode.statement('context /* ref */');
+    expect(block.asyncStateFor(reference), AsyncState.asynchronous);
+  }
+
   test_extensionOverride_referenceAfter_awaitInArgument() async {
     await resolveCode(r'''
 import 'package:flutter/widgets.dart';
@@ -369,6 +399,36 @@ void foo(BuildContext context, int i) async {
     expect(forElement.asyncStateFor(reference), AsyncState.mountedCheck);
   }
 
+  test_forStatement_referenceInBody_asyncInBody() async {
+    await resolveCode(r'''
+import 'package:flutter/widgets.dart';
+void foo(BuildContext context) async {
+  for (var a in []) {
+    await Future.value();
+    context /* ref */;
+  }
+}
+''');
+    var block = findNode.block('context /* ref */');
+    var reference = findNode.statement('context /* ref */');
+    expect(block.asyncStateFor(reference), AsyncState.asynchronous);
+  }
+
+  test_forStatement_referenceInBody_asyncInBody2() async {
+    await resolveCode(r'''
+import 'package:flutter/widgets.dart';
+void foo(BuildContext context) async {
+  for (var a in []) {
+    context /* ref */;
+    await Future.value();
+  }
+}
+''');
+    var block = findNode.block('context /* ref */');
+    var reference = findNode.statement('context /* ref */');
+    expect(block.asyncStateFor(reference), AsyncState.asynchronous);
+  }
+
   test_forStatementWithDeclaration_referenceAfter_awaitInPartCondition() async {
     await resolveCode(r'''
 import 'package:flutter/widgets.dart';
@@ -1604,6 +1664,26 @@ Future<void> f() async {}
     ]);
   }
 
+  test_awaitBeforeForBody_referenceToContext_thenMountedGuard() async {
+    // Await, then for-each statement, and inside the for-body: use of
+    // BuildContext, then mounted guard, is REPORTED.
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+void foo(BuildContext context) async {
+  await f();
+  for (var e in []) {
+    Navigator.of(context);
+    if (context.mounted) return;
+  }
+}
+
+Future<void> f() async {}
+''', [
+      lint(118, 21),
+    ]);
+  }
+
   test_awaitBeforeIfStatement_withReferenceToContext() async {
     // Await, then use of BuildContext in an unrelated if-body, is REPORTED.
     await assertDiagnostics(r'''
@@ -1654,7 +1734,6 @@ void foo(BuildContext context) async {
   }
 }
 
-bool mounted = false;
 Future<void> f() async {}
 ''', [
       lint(113, 21),
@@ -1877,6 +1956,63 @@ void foo(BuildContext context) async {
 
 ''');
   }
+
+  test_referenceToContextInDoWhileBody_thenAwait() async {
+    // Do-while statement, and inside the do-while-body: use of BuildContext,
+    // then await, is REPORTED.
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+void foo(BuildContext context) async {
+  do {
+    Navigator.of(context);
+    await f();
+  } while (true);
+}
+
+Future<void> f() async {}
+''', [
+      lint(90, 21),
+    ]);
+  }
+
+  test_referenceToContextInForBody_thenAwait() async {
+    // For-each statement, and inside the for-body: use of BuildContext, then
+    // await, is REPORTED.
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+void foo(BuildContext context) async {
+  for (var e in []) {
+    Navigator.of(context);
+    await f();
+  }
+}
+
+Future<void> f() async {}
+''', [
+      lint(105, 21),
+    ]);
+  }
+
+  test_referenceToContextInWhileBody_thenAwait() async {
+    // While statement, and inside the while-body: use of BuildContext, then
+    // await, is REPORTED.
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+void foo(BuildContext context) async {
+  while (true) {
+    Navigator.of(context);
+    await f();
+  }
+}
+
+Future<void> f() async {}
+''', [
+      lint(100, 21),
+    ]);
+  }
 }
 
 extension on AstNode {

diff --git a/test_data/rules/use_build_context_synchronously.dart b/test_data/rules/use_build_context_synchronously.dart
@@ -76,24 +76,6 @@ class _MyState extends State<MyWidget> {
     Navigator.of(context).pushNamed('routeName'); // LINT
   }
 
-  // Another conditional path.
-  void methodWithBuildContextParameter2a(BuildContext context) async {
-    bool f() => true;
-    while (f()) {
-      await Future<void>.delayed(Duration());
-    }
-    Navigator.of(context).pushNamed('routeName'); // LINT
-  }
-
-  // And another.
-  void methodWithBuildContextParameter2d(BuildContext context) async {
-    bool f() => true;
-    do {
-      await Future<void>.delayed(Duration());
-    } while (f());
-    Navigator.of(context).pushNamed('routeName'); // LINT
-  }
-
   void methodWithBuildContextParameter2g(BuildContext context) async {
     await Future<void>.delayed(Duration());
     switch (1) {