mock-sense

mock-sense is a CLI that scans unit test files for mock-related test smells:

• over-mocking, based on a mock-to-assertion ratio
• vacuous assertions that always pass
• dead mocks that are configured but never used
• unchecked mocks that are called without any follow-up assertion

Install

pnpm add -D mock-sense

Or run it locally in this repo:

pnpm install
pnpm build
node dist/index.js test/

Usage

mock-sense <path> [options]

Options:

• --threshold <n>: Mock/assert ratio threshold. Default: 3.0
• --json: Emit JSON instead of terminal output
• --no-fail: Report only. Do not exit with status 1 when issues are found
• --coverage: Show mock usage coverage for each test file
• --suggest: Suggest missing assertions from mock call patterns
• --ext <exts>: Comma-separated test file extensions. Default: .test.ts,.test.js,.spec.ts,.spec.js

What It Detects

Over-mocking

For each file, mock-sense counts lines matching mock patterns such as:

• jest.mock(
• vi.mock(
• sinon.stub(
• jest.fn(
• vi.fn(
• mock.
• .mockReturnValue(
• .mockResolvedValue(

It also counts assertion lines matching:

• expect(
• assert.
• should.

If mocks / assertions is greater than the configured threshold, the file is flagged as suspicious.

Vacuous Assertions

mock-sense flags assertions that always pass, including:

• assert.equal(true, true)
• assert.ok(true)
• assert.strictEqual(1, 1) and similar same-literal comparisons
• expect(true).toBe(true)
• assert.ok(undefined !== undefined)

Mock Coverage

mock-sense --coverage tracks locally defined mocks such as const sendEmail = jest.fn() and reports:

• mocks that are never called
• mocks that are called but never asserted on

Suggestions

mock-sense --suggest uses the same call analysis to recommend missing assertions such as:

• expect(sendEmail).toHaveBeenCalledWith(...)
• expect(result).toBeDefined() for unchecked mock return values

Examples

mock-sense test/

Analyzing 4 test files...

⚠  test/over-mocked.test.ts
   Mocks: 15 | Assertions: 2 | Ratio: 7.5 (suspicious, threshold: 3.0)

⚠  test/vacuous.test.ts
   Line 3: assert.equal(true, true)  ← vacuous assertion
   Line 4: assert.ok(undefined !== undefined)  ← vacuous assertion

✓  test/healthy.test.ts  (healthy)

Summary: 2 suspicious files, 2 vacuous assertions found.
Exit code: 1 (issues found)

mock-sense test --json --no-fail

Outputs structured JSON suitable for CI or custom reporting.

mock-sense test --coverage

mock-sense test --suggest