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Disallow the use of assert.equal/assert.ok/assert.notEqual/assert.notOk (qunit/no-loose-assertions)

The assert.equal/assert.notEqual assertion methods in QUnit use loose equality comparison. In a project which favors strict equality comparison, it is better to use assert.strictEqual/assert.notStrictEqual for scalar values and either assert.deepEqual or assert.propEqual for more complex objects.

assert.ok and assert.notOk pass for any truthy/falsy argument. As many expressions evaluate to true/false in JavaScript the usage of assert.ok is potentially error prone. In general, it should be advisable to always test for exact values in tests which makes tests a lot more solid.

An example when using assert.ok can involuntarily go wrong:

test('test myFunc returns a truthy value', (assert) => {
    assert.ok(myFunc);
});

Here by mistake a developer just passed to assert.ok a pointer to myFunc instead of explicitly calling it. This test is going pass no matter how myFunc changes. Using assert.strictEqual(myFunc, theReturnValue) solves the problem as this becomes an explicit check for equality.

Rule Details

The following patterns are considered warnings:

QUnit.test('Name', function (assert) { assert.ok(a); });

QUnit.test('Name', function (foo) { foo.ok(a); });

QUnit.test('Name', function () { ok(a); });

QUnit.test('Name', function (assert) { assert.notOk(a); });

QUnit.test('Name', function (foo) { foo.notOk(a); });

QUnit.test('Name', function () { notOk(a); });

QUnit.test('Name', function (assert) { assert.equal(a, b); });

QUnit.test('Name', function (foo) { foo.equal(a, b); });

QUnit.test('Name', function () { equal(a, b); });

QUnit.test('Name', function (assert) { assert.notEqual(a, b); });

QUnit.test('Name', function (foo) { foo.notEqual(a, b); });

QUnit.test('Name', function () { notEqual(a, b); });

The following patterns are not considered warnings:

QUnit.test('Name', function (assert) { assert.strictEqual(a, true); });

QUnit.test('Name', function (foo) { foo.strictEqual(a, true); });

QUnit.test('Name', function () { strictEqual(a, true); });

QUnit.test('Name', function (assert) { assert.notStrictEqual(a, false); });

QUnit.test('Name', function (foo) { foo.notStrictEqual(a, false); });

QUnit.test('Name', function () { notStrictEqual(a, false); });

QUnit.test('Name', function (assert) { assert.deepEqual(a, b); });

QUnit.test('Name', function (foo) { foo.deepEqual(a, b); });

QUnit.test('Name', function () { deepEqual(a, b); });

QUnit.test('Name', function (assert) { assert.propEqual(a, b); });

QUnit.test('Name', function (foo) { foo.propEqual(a, b); });

QUnit.test('Name', function () { propEqual(a, b); });

/* With rule config: ["error", ["strictEqual", "ok", "notOk"]] */
QUnit.test('Name', function (assert) { assert.notEqual(a, b); });

Options

The assertions to lint against can be controlled with an array of assertions (default ["equal", "notEqual", "ok", "notOk"]).

To fine tune the error message (which by default will recommend to use strictEqual, notStrictEqual, deepEqual, or propEqual) a configuration object can be passed as an option instead of a string. The configuration object has two properties:

  • disallowed: the name of the assertion to disallow (either equal, ok, or notOk);
  • recommended: an array of strings representing the recommended options to display as an error message. The strings in the array will be concatenated to build the error message: Unexpected {{assertVar}}.{{assertion}}. Use {{assertVar}}.<recommended_1>, {{assertVar}}.<recommended_2>. when using local assertions and Unexpected {{assertion}}. Use <recommended_1>, <recommended_2>. when using global assertions.

If an assertion is passed twice as a string and object the first configuration will be used and any other configuration will be ignored.

Further Reading