feat(mocha-to-node-test-runner) : Migrate Mocha v8 tests to Node.js test runner (v22, v24+) by Xstoudi · Pull Request #313 · nodejs/userland-migrations

Xstoudi · 2025-12-22T21:39:39Z

Should fix #103

AugustinMauroy

Oh nice that really cool !

Few points that can be improved:

md format on readme
little bit of JSdoc
small missing unit test

recipes/mocha-to-node-test-runner/README.md

recipes/mocha-to-node-test-runner/src/workflow.ts

utils/src/is-esm.ts

Co-authored-by: Augustin Mauroy <97875033+AugustinMauroy@users.noreply.github.com>

Xstoudi · 2025-12-23T19:12:27Z

I wrote test for is-esm, let me know if you see something is missing.

I applied your recommendations then reverted two of them:

one was changing logic wrongly
replacing array.length === 0 with !array.length make it less readable, I'd prefer to avoid doing so

Let me now if there is anything else.

AugustinMauroy · 2025-12-24T08:05:14Z

recipes/mocha-to-node-test-runner/tests/input/1_basic.js

+		it('should return -1 when the value is not present', function() {
+			const arr = [1, 2, 3];
+			assert.strictEqual(arr.indexOf(4), -1);
+		});


maybe add an other it that use arrow function as call back
and a fonction as arg like

function myBasicTest = () => { assert(true) }

The second case will be can super complicated to migrate.
in a first time let's just have test that proof that's ins't handled and document it.
In second time (follow up pr) having systems that handle this case. The logic to catch a refercen is already furnished by the codemod context https://docs.codemod.com/jssg/semantic-analysis

Xstoudi · 2025-12-26T22:08:12Z

Let me know if anything more is required.

AugustinMauroy

LGMT ! for the code transformation part missing the removing dep you should take code from chalk-to-styletext.

recipes/mocha-to-node-test-runner/README.md

Xstoudi · 2025-12-30T18:11:09Z

Added that, let me know if something is missing.

AugustinMauroy

For me it's good ! we need to wait a second approval to land !

AugustinMauroy · 2025-12-30T20:49:21Z

F*ck what happened here. !Windows!

cc @nodejs/userland-migrations any idea

brunocroh · 2026-01-05T21:15:54Z

recipes/mocha-to-node-test-runner/src/workflow.ts

+			},
+		},
+		rule: {
+			any: [{ pattern: '$MOCHA_GLOBAL_FN($$$)' }],


nit: unnecessary any

Suggested change

any: [{ pattern: '$MOCHA_GLOBAL_FN($$$)' }],

pattern: '$MOCHA_GLOBAL_FN($$$)',

brunocroh · 2026-01-05T22:31:49Z

recipes/mocha-to-node-test-runner/src/workflow.ts

+	if (esm) {
+		const importStatements = rootNode.findAll({
+			rule: { kind: 'import_statement' },
+		});
+		const lastImportStatement = importStatements[importStatements.length - 1];
+		if (lastImportStatement !== undefined) {
+			return [
+				{
+					startPos: lastImportStatement.range().end.index,
+					endPos: lastImportStatement.range().end.index,
+					insertedText,
+				},
+			];
+		}
+	} else {
+		const requireStatements = rootNode.findAll({
+			rule: { pattern: 'const $_A = require($_B)' },
+		});
+		const lastRequireStatements =
+			requireStatements[requireStatements.length - 1];
+		if (lastRequireStatements !== undefined) {
+			return [
+				{
+					startPos: lastRequireStatements.range().end.index,
+					endPos: lastRequireStatements.range().end.index,
+					insertedText,
+				},
+			];
+		}
+	}


Suggested change

if (esm) {

const importStatements = rootNode.findAll({

rule: { kind: 'import_statement' },

});

const lastImportStatement = importStatements[importStatements.length - 1];

if (lastImportStatement !== undefined) {

return [

{

startPos: lastImportStatement.range().end.index,

endPos: lastImportStatement.range().end.index,

insertedText,

},

];

}

} else {

const requireStatements = rootNode.findAll({

rule: { pattern: 'const $_A = require($_B)' },

});

const lastRequireStatements =

requireStatements[requireStatements.length - 1];

if (lastRequireStatements !== undefined) {

return [

{

startPos: lastRequireStatements.range().end.index,

endPos: lastRequireStatements.range().end.index,

insertedText,

},

];

}

}

const dependenciesStmt = rootNode.findAll({

rule: {

any: [

{ kind: 'import_statement' },

{

kind: 'lexical_declaration',

has: {

stopBy: 'end',

kind: 'call_expression',

has: {

kind: 'identifier',

regex: '^require$',

},

},

},

],

},

});

const lastDepStmt = dependenciesStmt.at(-1);

if (lastDepStmt !== undefined) {

return [

{

startPos: lastDepStmt.range().end.index,

endPos: lastDepStmt.range().end.index,

insertedText,

},

];

}

Please add tests that cover esm implementations

brunocroh · 2026-01-05T22:38:54Z

recipes/mocha-to-node-test-runner/src/workflow.ts

+function transformThisSkip(root: SgRoot<JS>): Edit[] {
+	const rootNode = root.root();
+	const thisSkipCalls = rootNode.findAll({
+		rule: { pattern: 'this.skip($$$)' },
+	});
+
+	return thisSkipCalls.flatMap((thisSkipCall) => {
+		const edits: Edit[] = [];
+		const memberExpr = thisSkipCall.find({
+			rule: { kind: 'member_expression', has: { kind: 'this' } },
+		});
+		if (memberExpr !== null) {
+			const thisKeyword = memberExpr.field('object');
+			if (thisKeyword !== null) {
+				edits.push(thisKeyword.replace('t'));
+			}
+		}
+
+		const enclosingFunction = thisSkipCall
+			.ancestors()
+			.find((ancestor) =>
+				['function_expression', 'arrow_function'].includes(ancestor.kind()),
+			);
+		if (enclosingFunction === undefined) {
+			return edits;
+		}
+
+		const parameters =
+			enclosingFunction.field('parameters') ??
+			enclosingFunction.field('parameter');
+		if (parameters === null) {
+			return edits;
+		}
+
+		if (parameters.kind() === 'identifier') {
+			edits.push(parameters.replace(`(t, ${parameters.text()})`));
+		} else if (parameters.kind() === 'formal_parameters') {
+			edits.push({
+				startPos: parameters.range().start.index + 1,
+				endPos: parameters.range().start.index + 1,
+				insertedText: `t${parameters.children().length > 2 ? ', ' : ''}`,
+			});
+		}
+
+		return edits;
+	});
+}
+
+function transformThisTimeout(root: SgRoot<JS>): Edit[] {
+	const rootNode = root.root();
+	const thisTimeoutCalls = rootNode.findAll({
+		rule: { pattern: 'this.timeout($TIME)' },
+	});
+
+	return thisTimeoutCalls.flatMap((thisTimeoutCall) => {
+		const edits = [] as Edit[];
+		const thisTimeoutExpression = thisTimeoutCall.parent();
+
+		const source = rootNode.text();
+		const startIndex = thisTimeoutExpression.range().start.index;
+		const endIndex = thisTimeoutExpression.range().end.index;
+
+		let lineStart = startIndex;
+		while (lineStart > 0 && source[lineStart - 1] !== EOL) lineStart--;
+		let lineEnd = endIndex;
+		while (lineEnd < source.length && source[lineEnd] !== EOL) lineEnd++;
+		if (lineEnd < source.length) lineEnd++;
+
+		edits.push({
+			startPos: lineStart,
+			endPos: lineEnd,
+			insertedText: '',
+		});
+
+		const enclosingFunction = thisTimeoutCall
+			.ancestors()
+			.find((ancestor) =>
+				['function_expression', 'arrow_function'].includes(ancestor.kind()),
+			);
+		if (enclosingFunction === undefined) {
+			return edits;
+		}
+
+		const time = thisTimeoutCall.getMatch('TIME').text();
+		edits.push({
+			startPos: enclosingFunction.range().start.index,
+			endPos: enclosingFunction.range().start.index,
+			insertedText: `{ timeout: ${time} }, `,
+		});
+		return edits;
+	});
+}


I think these this.skip and this.timeout handlers can be unified, looks like the same logic. what do you think?

AugustinMauroy · 2026-01-17T17:25:05Z

hey 👋 @Xstoudi

Xstoudi added 4 commits December 21, 2025 01:31

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Xstoudi changed the title ~~feature(mocha-to-node-test-runner) : Migrate Mocha v8 tests to Node.js test runner (v22, v24+)~~ feat(mocha-to-node-test-runner) : Migrate Mocha v8 tests to Node.js test runner (v22, v24+) Dec 22, 2025

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AugustinMauroy reviewed Dec 23, 2025

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Xstoudi and others added 2 commits December 23, 2025 19:12

Apply suggestions from code review

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Co-authored-by: Augustin Mauroy <97875033+AugustinMauroy@users.noreply.github.com>

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AugustinMauroy reviewed Dec 24, 2025

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AugustinMauroy reviewed Dec 28, 2025

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brunocroh added the awaiting author Reviewer has requested something from the author label Jan 9, 2026

	any: [{ pattern: '$MOCHA_GLOBAL_FN($$$)' }],
	pattern: '$MOCHA_GLOBAL_FN($$$)',

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Xstoudi commented Dec 22, 2025 •

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