Nested ExpressionStatements Issue #144

packages/ts-migrate-plugins/src/plugins/add-conversions.ts

@@ -43,7 +43,7 @@ const addConversionsTransformerFactory =
       : factory.createKeywordTypeNode(ts.SyntaxKind.AnyKeyword);
 
     let nodesToConvert: Set<ts.Node>;
-
+    const ancestorReplaceMap = new Map<ts.Node, boolean>();
     return (file: ts.SourceFile) => {
       nodesToConvert = new Set(
         diags
@@ -71,6 +71,14 @@ const addConversionsTransformerFactory =
     };
 
     function visit(origNode: ts.Node): ts.Node | undefined {
+      const ancestorShouldBeReplaced = ancestorReplaceMap.get(origNode.parent);
+      ancestorReplaceMap.set(
+        origNode,
+        ancestorShouldBeReplaced === undefined
+          ? origNode.kind === ts.SyntaxKind.ExpressionStatement
+          : origNode.kind === ts.SyntaxKind.ExpressionStatement || ancestorShouldBeReplaced,
+      );
+
       const needsConversion = nodesToConvert.has(origNode);
       let node = ts.visitEachChild(origNode, visit, context);
       if (node === origNode && !needsConversion) {
@@ -81,7 +89,7 @@ const addConversionsTransformerFactory =
         node = factory.createAsExpression(node as ts.Expression, anyType);
       }
 
-      if (shouldReplace(node)) {
+      if (shouldReplace(node) && !ancestorShouldBeReplaced) {
         replaceNode(origNode, node);
         return origNode;
       }

packages/ts-migrate-plugins/tests/src/add-conversions.test.ts

@@ -113,4 +113,22 @@ class PublishEvent {
 }
 `);
   });
+
+  it('Nested Expression Statements (issue #144) Part 1: Expression Statement -> Expression Statement', async () => {
+    const text = `var window = { onResetData: function () { this.clearNextPush = function () { this.setState({ history: [] }); }; } };`;
+    const result = addConversionsPlugin.run(await realPluginParams({ text }));
+
+    expect(result).toBe(
+      `var window = { onResetData: function () { (this as any).clearNextPush = function () { (this as any).setState({ history: [] }); }; } };`,
+    );
+  });
+
+  it('Nested Expression Statements (issue #144) Part 2: Expression Statement -> If Statement -> Expression Statement', async () => {
+    const text = `const window = { onResetData() { this.clearNextPush = function () {\n    if (this.setState) {\n    this.setState({ history: [] });\n} }; } };`;
+    const result = addConversionsPlugin.run(await realPluginParams({ text }));
+
+    expect(result).toBe(
+      `const window = { onResetData() { (this as any).clearNextPush = function () {\n    if ((this as any).setState) {\n        (this as any).setState({ history: [] });\n    }\n}; } };`,
+    );
+  });
 });