eslint-plugin-test-signal

eslint-plugin-test-signal reports tests that look green while proving too little about behavior.

The first rule set focuses on common weak-test signals:

• tests whose only assertion is a snapshot;
• tests whose only assertion inspects mock call metadata;
• assertions whose subject is a static constant;
• broad existence assertions that do not verify expected shape or value;
• assertions that compare a value to itself;
• vacuous whole-value asymmetric assertions;
• length assertions that only prove length is non-negative;
• fixed real-time waits that make tests slow or flaky;
• synthetic Promise assertions that do not exercise code under test;
• string and numeric assertions with vacuous expected values;
• broad object key-count assertions that only prove non-emptiness;
• duplicate assertion chains in the same test;
• Promise assertions that are not awaited or returned;
• async tests that contain no assertion;
• suites that have no negative-path coverage signal.

Design scope

The plugin uses syntax-level heuristics that work across Vitest, Jest-style APIs, and @typescript-eslint/rule-tester suites. It intentionally avoids type checker work because the targeted patterns are visible directly in the test AST.

Presets

• testSignal.configs.minimal enables the lowest-noise correctness rules.
• testSignal.configs.recommended adds weak assertion signal detection, including snapshot-only, mock-call-only, constant-subject, and broad existence assertions.
• testSignal.configs["recommended-type-checked"] currently matches recommended because no shipped rule requires parser services yet.
• testSignal.configs.strict adds negative-path coverage enforcement.
• testSignal.configs.all enables every stable rule.
• testSignal.configs.experimental is reserved for future candidate rules and currently matches all.

Rule reference

Rule	Purpose
no-empty-async-tests	Flags async tests without assertions.
require-awaited-async-assertions	Flags floating .resolves and .rejects assertions.
no-snapshot-only-tests	Flags tests whose only assertions are snapshots.
no-mock-call-only-tests	Flags tests whose only assertions inspect mock calls.
no-constant-assertions	Flags assertions whose subject is a static constant.
no-weak-existence-assertions	Flags broad existence assertions such as toBeDefined().
no-identical-expected-actual	Flags assertions that compare a value to itself.
no-weak-asymmetric-assertions	Flags vacuous whole-value asymmetric assertions.
no-tautological-length-assertions	Flags length assertions that only prove length is non-negative.
no-fixed-delay-tests	Flags fixed real-time delays in executable tests.
no-synthetic-promise-assertions	Flags .resolves and .rejects assertions against synthetic Promise values.
no-vacuous-string-assertions	Flags string assertions with expected values that match anything.
no-vacuous-numeric-assertions	Flags numeric bound assertions with infinite thresholds.
no-broad-object-key-count-assertions	Flags object key-count assertions that only prove an object is non-empty.
no-duplicate-assertions	Flags repeated identical assertion chains in the same test.
require-negative-path	Flags test scopes without negative-path coverage signals.