[Bug]: Reporter interface typing is too strong?

[liamjones]

Version

29.6.2

Steps to reproduce

1. Write a custom reporter in JavaScript that only implements onRunComplete, as documented here: https://jestjs.io/docs/configuration/#custom-reporters.
2. Check reporter works fine with Jest.
3. Migrate JS to TypeScript and implement Reporter (see https://codesandbox.io/s/sharp-babbage-6v54kc?file=/src/index.ts for example)

Expected behavior

No TypeScript errors

Actual behavior

TypeScript error:

Class 'CustomReporter' incorrectly implements interface 'Reporter'.
   Type 'CustomReporter' is missing the following properties from type 'Reporter': onRunStart, getLastErrorts(2420)

Additional context

No response

Environment

System:
    OS: macOS 13.5.1
    CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  Binaries:
    Node: 18.17.0 - ~/Library/Caches/fnm_multishells/11306_1692352089946/bin/node
    Yarn: 1.22.19 - ~/Library/Caches/fnm_multishells/11306_1692352089946/bin/yarn
    npm: 9.8.1 - ~/Library/Caches/fnm_multishells/11306_1692352089946/bin/npm
  npmPackages:
    jest: ^29.2.1 => 29.6.2

[SimenB]

They're all optional in reality, so PR very much welcome 🙂

jest/packages/jest-reporters/src/types.ts

Lines 22 to 56 in eb61702

	export interface Reporter {
	readonly onTestResult?: (
	test: Test,
	testResult: TestResult,
	aggregatedResult: AggregatedResult,
	) => Promise<void> | void;
	readonly onTestFileResult?: (
	test: Test,
	testResult: TestResult,
	aggregatedResult: AggregatedResult,
	) => Promise<void> | void;
	/**
	* Called before running a spec (prior to `before` hooks)
	* Not called for `skipped` and `todo` specs
	*/
	readonly onTestCaseStart?: (
	test: Test,
	testCaseStartInfo: Circus.TestCaseStartInfo,
	) => Promise<void> | void;
	readonly onTestCaseResult?: (
	test: Test,
	testCaseResult: TestCaseResult,
	) => Promise<void> | void;
	readonly onRunStart: (
	results: AggregatedResult,
	options: ReporterOnStartOptions,
	) => Promise<void> | void;
	readonly onTestStart?: (test: Test) => Promise<void> | void;
	readonly onTestFileStart?: (test: Test) => Promise<void> | void;
	readonly onRunComplete: (
	testContexts: Set<TestContext>,
	results: AggregatedResult,
	) => Promise<void> | void;
	readonly getLastError: () => Error | void;
	}

[liamjones]

They're all optional in reality

Even onRunComplete? The docs say:

"Custom reporter module must export a class that takes globalConfig, reporterOptions and reporterContext as constructor arguments and implements at least onRunComplete() method"

PR very much welcome

Sure! I can do one for the docs too if they're not accurate

[mrazauskas]

Hooks of the reporters are called here: jest/packages/jest-core/src/ReporterDispatcher.ts.

Looks like all are optional. Just as Simen said already.

[SimenB]

PR very much welcome

Sure! I can do one for the docs too if they're not accurate

yes please 😀

[quantumflo]

Hi, Is someone already creating a PR?
If not I can work on this issue.