New rule no-access-state-in-setstate (#190)

Author: cheeZery

README.md

@@ -52,6 +52,7 @@ The built-in configuration preset you get with `"extends": "tslint-react"` is se
       size={size}
   />
   ```
+  - Rule options: _none_
 - `jsx-ban-elements` (since v3.4.0)
   - Allows blacklisting of JSX elements with an optional explanatory message in the reported failure.
 - `jsx-ban-props` (since v2.3.0)
@@ -121,6 +122,22 @@ The built-in configuration preset you get with `"extends": "tslint-react"` is se
       </button>
   );
   ```
+  - Rule options: _none_
+- `no-access-state-in-setstate`
+  - Forbids accessing component state with `this.state` within `this.setState`
+  calls, since React might batch multiple `this.setState` calls, thus resulting
+  in accessing old state. Enforces use of callback argument instead.
+  ```ts
+  // bad
+  this.setState({
+      counter: this.state.counter + 1
+  });
+  // good
+  this.setState(
+      prevState => ({ counter: prevState.counter + 1 })
+  );
+  ```
+  - Rule options: _none_
 
 ### Development
 

src/rules/noAccessStateInSetstateRule.ts

@@ -0,0 +1,119 @@
+/**
+ * @license
+ * Copyright 2018 Palantir Technologies, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import * as Lint from "tslint";
+import { isCallExpression, isClassDeclaration, isPropertyAccessExpression } from "tsutils";
+import * as ts from "typescript";
+
+export class Rule extends Lint.Rules.AbstractRule {
+    /* tslint:disable:object-literal-sort-keys */
+    public static metadata: Lint.IRuleMetadata = {
+        ruleName: "no-access-state-in-setstate",
+        description: "Reports usage of this.state within setState",
+        rationale: Lint.Utils.dedent`
+            Usage of this.state might result in errors when two state calls are
+            called in batch and thus referencing old state and not the current state.
+            See [setState()](https://reactjs.org/docs/react-component.html#setstate) in the React API reference.
+        `,
+        options: null,
+        optionsDescription: "",
+        type: "functionality",
+        typescriptOnly: false,
+    };
+    /* tslint:enable:object-literal-sort-keys */
+
+    public static OBJECT_ARG_FAILURE =
+        "References to this.state are not allowed in the setState state change object.";
+
+    public static CALLBACK_ARG_FAILURE =
+        "References to this.state are not allowed in the setState updater, use the callback arguments instead.";
+
+    public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+        return this.applyWithFunction(sourceFile, walk);
+    }
+}
+
+function walk(ctx: Lint.WalkContext<void>): void {
+    return ts.forEachChild(ctx.sourceFile, callbackForEachChild);
+
+    function callbackForEachChild(node: ts.Node): void {
+        if (!isClassDeclaration(node)) {
+            return;
+        }
+
+        ts.forEachChild(node, callbackForEachChildInClass);
+    }
+
+    function callbackForEachChildInClass(node: ts.Node): void {
+        if (!isCallExpression(node)) {
+            return ts.forEachChild(node, callbackForEachChildInClass);
+        }
+
+        const callExpressionArguments = node.arguments;
+
+        if (!isPropertyAccessExpression(node.expression) || callExpressionArguments.length === 0) {
+            return;
+        }
+
+        const propertyAccessExpression = node.expression;
+
+        const isThisPropertyAccess = propertyAccessExpression.expression.kind === ts.SyntaxKind.ThisKeyword;
+        const isSetStateCall = propertyAccessExpression.name.text === "setState";
+
+        if (!isThisPropertyAccess || !isSetStateCall) {
+            return;
+        }
+
+        const firstArgument = node.arguments[0];
+
+        if (ts.isObjectLiteralExpression(firstArgument)) {
+            ts.forEachChild(firstArgument, callbackForEachChildInSetStateObjectArgument);
+        } else if (ts.isArrowFunction(firstArgument) || ts.isFunctionExpression(firstArgument)) {
+            ts.forEachChild(firstArgument, callbackForEachChildInSetStateCallbackArgument);
+        }
+    }
+
+    function callbackForEachChildInSetStateObjectArgument(node: ts.Node): void {
+        if (!isPropertyAccessExpression(node) || !isPropertyAccessExpression(node.expression)) {
+            return ts.forEachChild(node, callbackForEachChildInSetStateObjectArgument);
+        }
+
+        if (
+            node.expression.expression.kind !== ts.SyntaxKind.ThisKeyword ||
+            node.expression.name.text !== "state"
+        ) {
+            return ts.forEachChild(node, callbackForEachChildInSetStateObjectArgument);
+        }
+
+        ctx.addFailureAtNode(node, Rule.OBJECT_ARG_FAILURE);
+    }
+
+    function callbackForEachChildInSetStateCallbackArgument(node: ts.Node): void {
+        if (!isPropertyAccessExpression(node) || !isPropertyAccessExpression(node.expression)) {
+            return ts.forEachChild(node, callbackForEachChildInSetStateCallbackArgument);
+        }
+
+        if (
+            node.expression.expression.kind !== ts.SyntaxKind.ThisKeyword ||
+            node.expression.name.text !== "state"
+        ) {
+            return ts.forEachChild(node, callbackForEachChildInSetStateCallbackArgument);
+        }
+
+        ctx.addFailureAtNode(node, Rule.CALLBACK_ARG_FAILURE);
+    }
+}

test/rules/no-access-state-in-setstate/test.tsx.lint

@@ -0,0 +1,65 @@
+class SomeReactComponent extends React.Component {
+
+    someClassFunction() {
+
+        this.fooBar({
+            foo: this.state.foo
+        });
+
+        this.setState({
+            foo: "foo",
+            bar: this.barz
+        });
+
+        this.setState(
+            {
+                foo: "foo"
+            },
+            () => this.fooBar(this.state.foo);
+        );
+
+        this.setState(prevState => ({
+            foo: !prevState.foo
+        }));
+
+        this.setState((prevState, currentProps) => ({
+            foo: !prevState.foo,
+            bar: currentProps.bar
+        }));
+
+        this.setState({
+            foo: window.history.length
+        });
+
+        this.setState({
+            foo: !this.props.bar
+        });
+
+        this.setState({
+            foo: !this.state.foo
+                  ~~~~~~~~~~~~~~ [0]
+        });
+
+        this.setState({
+            foo: this.fooBar(this.state.foo)
+                             ~~~~~~~~~~~~~~ [0]
+        });
+
+        this.setState((prevState, currentProps) => ({
+            foo: !this.state.foo,
+                  ~~~~~~~~~~~~~~ [1]
+            bar: currentProps.bar
+        }));
+
+        this.setState((prevState, currentProps) => {
+            this.fooBar(this.state.foo);
+                        ~~~~~~~~~~~~~~ [1]
+            return {
+                bar: !prevState.bar
+            };
+        });
+    }
+}
+
+[0]: References to this.state are not allowed in the setState state change object.
+[1]: References to this.state are not allowed in the setState updater, use the callback arguments instead.

test/rules/no-access-state-in-setstate/tslint.json

@@ -0,0 +1,5 @@
+{
+    "rules": {
+        "no-access-state-in-setstate": true
+    }
+}