Support undefined as second argument to t.throws and t.throwsAsync

Author: stavalfi

index.d.ts

@@ -245,16 +245,11 @@ export interface SnapshotAssertion {
 }
 
 export interface ThrowsAssertion {
-	/**
-	 * Assert that the function throws [an error](https://www.npmjs.com/package/is-error). If so, returns the error value.
-	 */
-	<ThrownError extends Error>(fn: () => any, expectations?: null, message?: string): ThrownError;
-
 	/**
 	 * Assert that the function throws [an error](https://www.npmjs.com/package/is-error). If so, returns the error value.
 	 * The error must satisfy all expectations.
 	 */
-	<ThrownError extends Error>(fn: () => any, expectations: ThrowsExpectation, message?: string): ThrownError;
+	<ThrownError extends Error>(fn: () => any, expectations?: ThrowsExpectation | null, message?: string): ThrownError;
 
 	/** Skip this assertion. */
 	skip(fn: () => any, expectations?: any, message?: string): void;

lib/assert.js

@@ -73,7 +73,7 @@ function getErrorWithLongStackTrace() {
 }
 
 function validateExpectations(assertion, expectations, numArgs) { // eslint-disable-line complexity
-	if (numArgs === 1 || expectations === null) {
+	if (numArgs === 1 || expectations === null || expectations === undefined) {
 		expectations = {};
 	} else if (
 		typeof expectations === 'function' ||
@@ -85,7 +85,7 @@ function validateExpectations(assertion, expectations, numArgs) { // eslint-disa
 	) {
 		throw new AssertionError({
 			assertion,
-			message: `The second argument to \`t.${assertion}()\` must be an expectation object or \`null\``,
+			message: `The second argument to \`t.${assertion}()\` must be an expectation object, \`null\` or \`undefined\``,
 			values: [formatWithLabel('Called with:', expectations)]
 		});
 	} else {

test/assert.js

@@ -937,13 +937,18 @@ test('.throws()', gather(t => {
 		}, null);
 	});
 
-	// Regression test for https://github.com/avajs/ava/issues/1676
-	fails(t, () => {
+	passes(t, () => {
 		assertions.throws(() => {
 			throw new Error('foo');
 		}, undefined);
 	});
 
+	passes(t, async () => {
+		await assertions.throwsAsync(() => {
+			return Promise.reject(new Error('foo'));
+		}, undefined);
+	});
+
 	failsWith(t, () => {
 		assertions.throws(() => {}, null, null);
 	}, {
@@ -1085,47 +1090,47 @@ test('.throws() fails if passed a bad expectation', t => {
 		assertions.throws(() => {}, true);
 	}, {
 		assertion: 'throws',
-		message: 'The second argument to `t.throws()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throws()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /true/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throws(() => {}, 'foo');
 	}, {
 		assertion: 'throws',
-		message: 'The second argument to `t.throws()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throws()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /foo/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throws(() => {}, /baz/);
 	}, {
 		assertion: 'throws',
-		message: 'The second argument to `t.throws()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throws()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /baz/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throws(() => {}, class Bar {});
 	}, {
 		assertion: 'throws',
-		message: 'The second argument to `t.throws()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throws()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /Bar/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throws(() => {}, {});
 	}, {
 		assertion: 'throws',
-		message: 'The second argument to `t.throws()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throws()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /\{\}/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throws(() => {}, []);
 	}, {
 		assertion: 'throws',
-		message: 'The second argument to `t.throws()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throws()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /\[\]/}]
 	});
 
@@ -1177,47 +1182,47 @@ test('.throwsAsync() fails if passed a bad expectation', t => {
 		assertions.throwsAsync(() => {}, true);
 	}, {
 		assertion: 'throwsAsync',
-		message: 'The second argument to `t.throwsAsync()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throwsAsync()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /true/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throwsAsync(() => {}, 'foo');
 	}, {
 		assertion: 'throwsAsync',
-		message: 'The second argument to `t.throwsAsync()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throwsAsync()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /foo/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throwsAsync(() => {}, /baz/);
 	}, {
 		assertion: 'throwsAsync',
-		message: 'The second argument to `t.throwsAsync()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throwsAsync()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /baz/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throwsAsync(() => {}, class Bar {});
 	}, {
 		assertion: 'throwsAsync',
-		message: 'The second argument to `t.throwsAsync()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throwsAsync()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /Bar/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throwsAsync(() => {}, {});
 	}, {
 		assertion: 'throwsAsync',
-		message: 'The second argument to `t.throwsAsync()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throwsAsync()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /\{\}/}]
 	});
 
 	failsWith(t, () => {
 		assertions.throwsAsync(() => {}, []);
 	}, {
 		assertion: 'throwsAsync',
-		message: 'The second argument to `t.throwsAsync()` must be an expectation object or `null`',
+		message: 'The second argument to `t.throwsAsync()` must be an expectation object, `null` or `undefined`',
 		values: [{label: 'Called with:', formatted: /\[\]/}]
 	});