feat: add TypeScript type annotation tests with node 22 snapshots

biome.json

@@ -13,6 +13,12 @@
 		"enabled": true
 	},
 	"files": {
-		"ignore": ["dist/**", "deps/**", "lib/**", "node_modules/**"]
+		"ignore": [
+			"dist/**",
+			"deps/**",
+			"lib/**",
+			"node_modules/**",
+			"test/snapshot/**"
+		]
 	}
 }

package.json

@@ -23,7 +23,8 @@
 		"postpack": "npm run clean",
 		"build": "rspack build",
 		"typecheck": "tsc --noEmit",
-		"test": "node --test ./test"
+		"test": "node --test --experimental-test-snapshots ./test/*.test.js",
+		"test:regenerate": "node --test --experimental-test-snapshots --test-update-snapshots ./test/*.test.js"
 	},
 	"devDependencies": {
 		"@biomejs/biome": "1.8.3",

test/index.test.js

@@ -1,9 +1,98 @@
-const { test } = require("node:test");
-const assert = require("node:assert");
+const { test, snapshot } = require("node:test");
+const assert = require("node:assert/strict");
 const { transformSync } = require("../dist/index.js");
+const path = require("node:path");
 
-test("should perform type stripping", () => {
-	assert.strictEqual(typeof transformSync, "function");
+// Set the path for the snapshots directory
+snapshot.setResolveSnapshotPath((testPath) => {
+	return path.join(
+		__dirname,
+		"snapshots",
+		`${path.basename(testPath)}.snapshot`,
+	);
+});
+
+test("should perform type stripping", async (t) => {
 	const { code } = transformSync("const foo: string = 'bar';");
-	assert.strictEqual(code, "const foo         = 'bar';");
+	t.assert.snapshot(code);
+});
+
+test("should strip type annotations from functions", async (t) => {
+	const inputCode = "function greet(name: string): void { console.log(name); }";
+	const { code } = transformSync(inputCode);
+	t.assert.snapshot(code);
+});
+
+test("should strip type annotations from classes", async (t) => {
+	const inputCode = `
+    class MyClass {
+      myMethod(param: number): string {
+        return param.toString();
+      }
+    }
+  `;
+	const { code } = transformSync(inputCode);
+	t.assert.snapshot(code);
+});
+
+test("should strip type annotations from interfaces", async (t) => {
+	const inputCode = `
+    interface MyInterface {
+      myMethod(param: number): string;
+    }
+  `;
+	const { code } = transformSync(inputCode);
+	t.assert.snapshot(code);
+});
+
+test("should strip type annotations from type aliases", async (t) => {
+	const inputCode = `
+    type MyType = string | number;
+  `;
+	const { code } = transformSync(inputCode);
+	t.assert.snapshot(code);
+});
+
+test("should strip type annotations from generics", async (t) => {
+	const inputCode = `
+    function identity<T>(arg: T): T {
+      return arg;
+    }
+  `;
+	const { code } = transformSync(inputCode);
+	t.assert.snapshot(code);
+});
+
+test("should strip type annotations from arrow functions", async (t) => {
+	const inputCode = `
+    const greet = (name: string): void => {
+      console.log(name);
+    };
+  `;
+	const { code } = transformSync(inputCode);
+	t.assert.snapshot(code);
+});
+
+test("should strip type annotations from type assertions", async (t) => {
+	const inputCode = `
+    let someValue: any = "this is a string";
+    let strLength: number = (someValue as string).length;
+  `;
+	const { code } = transformSync(inputCode);
+	t.assert.snapshot(code);
+});
+
+test("should handle User type and isAdult function", async (t) => {
+	const inputCode = `
+    type User = {
+      name: string;
+      age: number;
+    };
+
+    function isAdult(user: User): boolean {
+      return user.age >= 18;
+    }
+  `;
+	const { code } = transformSync(inputCode);
+	t.assert.snapshot(code);
 });

test/setup.mjs

@@ -0,0 +1,3 @@
+register("some-typescript-loader");
+// TypeScript is supported hereafter
+// BUT other test/setup.*.mjs files still must be plain JavaScript!

test/snapshots/index.test.js.snapshot

@@ -0,0 +1,35 @@
+exports[`should handle User type and isAdult function 1`] = `
+"\\n                 \\n                   \\n                  \\n      \\n\\n    function isAdult(user      )          {\\n      return user.age >= 18;\\n    }\\n  "
+`;
+
+exports[`should perform type stripping 1`] = `
+"const foo         = 'bar';"
+`;
+
+exports[`should strip type annotations from arrow functions 1`] = `
+"\\n    const greet = (name        )       => {\\n      console.log(name);\\n    };\\n  "
+`;
+
+exports[`should strip type annotations from classes 1`] = `
+"\\n    class MyClass {\\n      myMethod(param        )         {\\n        return param.toString();\\n      }\\n    }\\n  "
+`;
+
+exports[`should strip type annotations from functions 1`] = `
+"function greet(name        )       { console.log(name); }"
+`;
+
+exports[`should strip type annotations from generics 1`] = `
+"\\n    function identity   (arg   )    {\\n      return arg;\\n    }\\n  "
+`;
+
+exports[`should strip type annotations from interfaces 1`] = `
+"\\n                           \\n                                      \\n     \\n  "
+`;
+
+exports[`should strip type annotations from type aliases 1`] = `
+"\\n                                  \\n  "
+`;
+
+exports[`should strip type annotations from type assertions 1`] = `
+"\\n    let someValue      = \\"this is a string\\";\\n    let strLength         = (someValue          ).length;\\n  "
+`;

test/snapshots/snapshot-config.js

@@ -0,0 +1,11 @@
+const { basename, dirname, extname, join } = require("node:path");
+const { snapshot } = require("node:test");
+
+snapshot.setResolveSnapshotPath(generateSnapshotPath);
+
+function generateSnapshotPath(testFilePath) {
+	const ext = extname(testFilePath);
+	const filename = basename(testFilePath, ext);
+	const base = dirname(testFilePath);
+	return join(base, `${filename}.snap.cjs`);
+}