Add codemod for required initial value in useRef (#217)

* Add codemod for required initial value in `useRef` * Rebase * Format
eps1lon · Dec 5, 2023 · 0047404 · 0047404
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diff --git a/.changeset/fifty-cheetahs-dance.md b/.changeset/fifty-cheetahs-dance.md
@@ -0,0 +1,8 @@
+---
+"types-react-codemod": minor
+---
+
+Add codemod for required initial value in `useRef`
+
+Added as `experimental-useRef-required-initial`.
+Can be used on 18.x types but only intended for once https://github.com/DefinitelyTyped/DefinitelyTyped/pull/64920 lands.
diff --git a/README.md b/README.md
@@ -38,8 +38,8 @@ Positionals:
      "deprecated-react-text", "deprecated-react-type", "deprecated-sfc-element",
                              "deprecated-sfc", "deprecated-stateless-component",
         "deprecated-void-function-component", "experimental-refobject-defaults",
-                    "implicit-children", "preset-18", "preset-19", "scoped-jsx",
-                                                     "useCallback-implicit-any"]
+       "experimental-useRef-required-initial", "implicit-children", "preset-18",
+                          "preset-19", "scoped-jsx", "useCallback-implicit-any"]
   paths                                                      [string] [required]
 
 Options:
@@ -267,7 +267,7 @@ In earlier versions of `@types/react` this codemod would change the typings.
 
 ### `experimental-refobject-defaults`
 
-WARNING: This is an experimental codemod to intended for codebases using published types.
+WARNING: This is an experimental codemod to intended for codebases using unpublished types.
 Only use if you're using https://github.com/DefinitelyTyped/DefinitelyTyped/pull/64896.
 
 `RefObject` no longer makes `current` nullable by default
@@ -307,6 +307,31 @@ If the import style doesn't match your preferences, you should set up auto-fixab
 +const element: React.JSX.Element = <div />;
 ```
 
+### `experimental-useRef-required-initial`
+
+WARNING: This is an experimental codemod to intended for codebases using unpublished types.
+Only use if you're using https://github.com/DefinitelyTyped/DefinitelyTyped/pull/64920.
+
+`useRef` now always requires an initial value.
+Implicit `undefined` is forbidden
+
+```diff
+ import * as React from "react";
+-React.useRef()
++React.useRef(undefined)
+```
+
+#### `experimental-useRef-required-initial` false-negative pattern A
+
+Importing `useRef` via aliased named import will result in the transform being skipped.
+
+```tsx
+import { useRef as useReactRef } from "react";
+
+// not transformed
+useReactRef<number>();
+```
+
 ## Supported platforms
 
 The following list contains officially supported runtimes.

diff --git a/bin/__tests__/types-react-codemod.js b/bin/__tests__/types-react-codemod.js
@@ -25,8 +25,8 @@ describe("types-react-codemod", () => {
 		     "deprecated-react-text", "deprecated-react-type", "deprecated-sfc-element",
 		                             "deprecated-sfc", "deprecated-stateless-component",
 		        "deprecated-void-function-component", "experimental-refobject-defaults",
-		                    "implicit-children", "preset-18", "preset-19", "scoped-jsx",
-		                                                     "useCallback-implicit-any"]
+		       "experimental-useRef-required-initial", "implicit-children", "preset-18",
+		                          "preset-19", "scoped-jsx", "useCallback-implicit-any"]
 		  paths                                                      [string] [required]
 
 		Options:

diff --git a/transforms/__tests__/preset-19.js b/transforms/__tests__/preset-19.js
@@ -7,6 +7,8 @@ describe("preset-19", () => {
 	let deprecatedReactChildTransform;
 	let deprecatedReactTextTransform;
 	let deprecatedVoidFunctionComponentTransform;
+	let refobjectDefaultsTransform;
+	let useRefRequiredInitialTransform;
 
 	function applyTransform(source, options = {}) {
 		return JscodeshiftTestUtils.applyTransform(preset19Transform, options, {
@@ -33,6 +35,12 @@ describe("preset-19", () => {
 		deprecatedVoidFunctionComponentTransform = mockTransform(
 			"../deprecated-void-function-component",
 		);
+		refobjectDefaultsTransform = mockTransform(
+			"../experimental-refobject-defaults",
+		);
+		useRefRequiredInitialTransform = mockTransform(
+			"../experimental-useRef-required-initial",
+		);
 
 		preset19Transform = require("../preset-19");
 	});
@@ -53,11 +61,15 @@ describe("preset-19", () => {
 				"deprecated-react-child",
 				"deprecated-react-text",
 				"deprecated-void-function-component",
+				"experimental-refobject-defaults",
+				"experimental-useRef-required-initial",
 			].join(","),
 		});
 
 		expect(deprecatedReactChildTransform).toHaveBeenCalled();
 		expect(deprecatedReactTextTransform).toHaveBeenCalled();
 		expect(deprecatedVoidFunctionComponentTransform).toHaveBeenCalled();
+		expect(refobjectDefaultsTransform).toHaveBeenCalled();
+		expect(useRefRequiredInitialTransform).toHaveBeenCalled();
 	});
 });
diff --git a/transforms/__tests__/useRef-required-initial.js b/transforms/__tests__/useRef-required-initial.js
@@ -0,0 +1,65 @@
+const { describe, expect, test } = require("@jest/globals");
+const dedent = require("dedent");
+const JscodeshiftTestUtils = require("jscodeshift/dist/testUtils");
+const useRefRequiredInitial = require("../experimental-useRef-required-initial");
+
+function applyTransform(source, options = {}) {
+	return JscodeshiftTestUtils.applyTransform(useRefRequiredInitial, options, {
+		path: "test.tsx",
+		source: dedent(source),
+	});
+}
+
+describe("transform useRef-required-initial", () => {
+	test("not modified", () => {
+		expect(
+			applyTransform(`
+			import * as React from 'react';
+			interface Props {
+				children?: ReactNode;
+			}
+    `),
+		).toMatchInlineSnapshot(`
+		"import * as React from 'react';
+		interface Props {
+			children?: ReactNode;
+		}"
+	`);
+	});
+
+	test("named import", () => {
+		expect(
+			applyTransform(`
+        import { useRef } from 'react';
+				const myRef = useRef<number>();
+      `),
+		).toMatchInlineSnapshot(`
+		"import { useRef } from 'react';
+		const myRef = useRef<number>(undefined);"
+	`);
+	});
+
+	test("false-negative named renamed import", () => {
+		expect(
+			applyTransform(`
+        import { useRef as useReactRef } from 'react';
+        const myRef = useReactRef<number>();
+      `),
+		).toMatchInlineSnapshot(`
+		"import { useRef as useReactRef } from 'react';
+		const myRef = useReactRef<number>();"
+	`);
+	});
+
+	test("namespace import", () => {
+		expect(
+			applyTransform(`
+				import * as React from 'react';
+				const myRef = React.useRef<number>();
+      `),
+		).toMatchInlineSnapshot(`
+		"import * as React from 'react';
+		const myRef = React.useRef<number>(undefined);"
+	`);
+	});
+});
diff --git a/transforms/experimental-useRef-required-initial.js b/transforms/experimental-useRef-required-initial.js
@@ -0,0 +1,42 @@
+const parseSync = require("./utils/parseSync");
+const t = require("@babel/types");
+const traverse = require("@babel/traverse").default;
+
+/**
+ * @type {import('jscodeshift').Transform}
+ *
+ * Summary for Klarna's klapp@?
+ * TODO
+ */
+const useRefRequiredInitialTransform = (file) => {
+	const ast = parseSync(file);
+
+	let changedSome = false;
+
+	// ast.get("program").value is sufficient for unit tests but not actually running it on files
+	// TODO: How to test?
+	const traverseRoot = ast.paths()[0].value;
+	traverse(traverseRoot, {
+		CallExpression({ node: callExpression }) {
+			const isUseRefCall =
+				(callExpression.callee.type === "Identifier" &&
+					callExpression.callee.name === "useRef") ||
+				(callExpression.callee.type === "MemberExpression" &&
+					callExpression.callee.property.type === "Identifier" &&
+					callExpression.callee.property.name === "useRef");
+
+			if (isUseRefCall && callExpression.arguments.length === 0) {
+				changedSome = true;
+				callExpression.arguments = [t.identifier("undefined")];
+			}
+		},
+	});
+
+	// Otherwise some files will be marked as "modified" because formatting changed
+	if (changedSome) {
+		return ast.toSource();
+	}
+	return file.source;
+};
+
+module.exports = useRefRequiredInitialTransform;
diff --git a/transforms/preset-19.js b/transforms/preset-19.js
@@ -3,6 +3,7 @@ const deprecatedReactTextTransform = require("./deprecated-react-text");
 const deprecatedVoidFunctionComponentTransform = require("./deprecated-void-function-component");
 const refobjectDefaultsTransform = require("./experimental-refobject-defaults");
 const scopedJsxTransform = require("./scoped-jsx");
+const useRefRequiredInitialTransform = require("./experimental-useRef-required-initial");
 
 /**
  * @type {import('jscodeshift').Transform}
@@ -24,12 +25,15 @@ const transform = (file, api, options) => {
 	if (transformNames.has("deprecated-void-function-component")) {
 		transforms.push(deprecatedVoidFunctionComponentTransform);
 	}
-	if (transformNames.has("plain-refs")) {
+	if (transformNames.has("experimental-refobject-defaults")) {
 		transforms.push(refobjectDefaultsTransform);
 	}
 	if (transformNames.has("scoped-jsx")) {
 		transforms.push(scopedJsxTransform);
 	}
+	if (transformNames.has("experimental-useRef-required-initial")) {
+		transforms.push(useRefRequiredInitialTransform);
+	}
 
 	let wasAlwaysSkipped = true;
 	const newSource = transforms.reduce((currentFileSource, transform) => {