Skip to main content

no-duplicate-assertions

Disallow repeated identical assertion chains in the same test.

Rule detailsโ€‹

Repeating the exact same assertion in one test does not add coverage. It usually signals copy-paste drift where the second assertion was meant to check a different field, expected value, or post-action state.

Incorrectโ€‹

it("returns user metadata", () => {
    const user = loadUser();

    expect(user.id).toBe("user-1");
    expect(user.id).toBe("user-1");
});

Correctโ€‹

it("returns user metadata", () => {
    const user = loadUser();

    expect(user.id).toBe("user-1");
    expect(user.name).toBe("Ada");
});
it("checks state transitions", () => {
    expect(store.getState()).toBe("idle");
    store.load();
    expect(store.getState()).toBe("loaded");
});

What this rule reportsโ€‹

This rule reports executable it(...) and test(...) callbacks that contain the same assertion chain more than once. Whitespace is ignored when comparing assertions, but the rule does not attempt semantic alias analysis.

Nested helper functions are ignored so reusable assertion helpers can keep their own local structure.

Optionsโ€‹

This rule has no options.

When not to use itโ€‹

Disable this rule for tests that intentionally repeat the same assertion around side effects to document invariants. In most cases, use a distinct expected value or assertion subject instead.

Rule catalog ID: R025