feat(rstest): add prefer-to-have-been-called-times rule - #2230

Summary

Add rstest/prefer-to-have-been-called-times to report toHaveLength() assertions on a mock's mock.calls array and rewrite them to toHaveBeenCalledTimes(). It is registered in the Rstest plugin without being added to the recommended preset, matching upstream.

The table of Chai matchers that replace the assertion subject and the predicate for a numeric literal written in source move to internal/utils/test_framework, behind IsSubjectMutatingChaiMatcher and StaticNumericLiteral, shared with rstest/prefer-to-have-length so the two rules cannot drift apart.

Credits

Port from eslint-plugin-jest's prefer-to-have-been-called-times.

Intentional differences from upstream

• Identifier bracket keys are not treated as member names. expect(handler[mock].calls) reads a variable rather than the mock property, so reporting and rewriting it would be a false positive.
• Dynamic matcher names are not reported. expect(handler.mock.calls)[matcher](2) names its matcher through a variable, which the assertion parser does not resolve to toHaveLength.
• Parenthesized links inside the subject are rewritten correctly. Upstream deletes one accessor chain as a single span and turns expect((handler.mock).calls).toHaveLength(2) into unparseable code.
• Optional chaining on the matcher is preserved. Upstream rewrites the whole matcher member, which drops the ?. in expect(handler.mock.calls)?.toHaveLength(2).
• Computed accessor delimiters are preserved. Upstream rewrites expect(handler.mock.calls)["toHaveLength"](2) to a dotted accessor; this port changes only the literal value.
• expect.soft assertions are checked. Soft assertions record the same call count, so they are treated like ordinary assertions.
• Matchers after a subject-changing Chai matcher are not reported. expect(handler.mock.calls).property(0).toHaveLength(2) measures the arguments of one recorded call rather than the call count, so the chain ends at property.
• expect.poll assertions are not checked. expect.poll takes a callback, so the only shape this rule could match there is an argument that throws before any matcher runs.
• Only a count written as a number is fixed. toHaveLength compares loosely and toHaveBeenCalledTimes strictly, so rewriting toHaveLength('1') fails an assertion that passed and rewriting not.toHaveLength('1') passes one that failed.
• Arguments that can reset the mock are reported without a fix. expect() captures the calls array while toHaveBeenCalledTimes reads mock.calls when the matcher runs, so expect(handler.mock.calls, (handler.mockClear(), 'called once')) would change result after the rewrite.
• A super receiver is reported without a fix. A bare super is not a value, so expect(super.mock.calls) cannot become expect(super) without producing code that does not parse.
• Assertions whose result is reused are reported without a fix. Rstest matchers return a Chai assertion that carries the rewritten subject into every later matcher, so only standalone assertion statements are fixed.

Known gaps

• expect.extend overrides are not consulted. A file-local override of toHaveLength or toHaveBeenCalledTimes changes what either matcher means, and no matcher-rewrite rule in the plugin checks IsExpectMatcherOverridden today; making this one the exception would be inconsistent, so it is left for a separate change covering the whole family.

Related Links

Related #935

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).