Update t.like to support Symbol keys and ignore non-enumerable properties

Fixes avajs#3208

Author: gibson042

docs/03-assertions.md

@@ -141,7 +141,7 @@ Assert that `actual` is not deeply equal to `expected`. The inverse of `.deepEqu
 
 Assert that `actual` is like `selector`. This is a variant of `.deepEqual()`, however `selector` does not need to have the same enumerable properties as `actual` does.
 
-Instead AVA derives a *comparable* value from `actual`, recursively based on the shape of `selector`. This value is then compared to `selector` using `.deepEqual()`.
+Instead AVA derives a *comparable* value from `actual`, recursively based on the enumerable shape of `selector`. This value is then compared to `selector` using `.deepEqual()`.
 
 Any values in `selector` that are not arrays or regular objects should be deeply equal to the corresponding values in `actual`.
 

lib/like-selector.js

@@ -1,18 +1,17 @@
 const isPrimitive = val => val === null || typeof val !== 'object';
 
 export function isLikeSelector(selector) {
-	if (isPrimitive(selector)) {
+	// Require selector to be an array or plain object.
+	if (
+		isPrimitive(selector)
+		|| !Array.isArray(selector) && Reflect.getPrototypeOf(selector) !== Object.prototype
+	) {
 		return false;
 	}
 
-	const keyCount = Reflect.ownKeys(selector).length;
-	if (Array.isArray(selector)) {
-		// In addition to `length`, require at at least one element.
-		return keyCount > 1;
-	} else {
-		// Require a plain object with at least one property.
-		return Reflect.getPrototypeOf(selector) === Object.prototype && keyCount > 0;
-	}
+	// Also require at least one enumerable property.
+	const descriptors = Object.getOwnPropertyDescriptors(selector);
+	return Reflect.ownKeys(descriptors).some(key => descriptors[key].enumerable === true);
 }
 
 export const CIRCULAR_SELECTOR = new Error('Encountered a circular selector');
@@ -29,7 +28,9 @@ export function selectComparable(actual, selector, circular = new Set()) {
 	}
 
 	const comparable = Array.isArray(selector) ? [] : {};
-	for (const [key, subselector] of Object.entries(selector)) {
+	const enumerableSubselectors = {...selector};
+	for (const key of Reflect.ownKeys(enumerableSubselectors)) {
+		const subselector = enumerableSubselectors[key];
 		comparable[key] = isLikeSelector(subselector)
 			? selectComparable(Reflect.get(actual, key), subselector, circular)
 			: Reflect.get(actual, key);

test-tap/assert.js

@@ -720,7 +720,7 @@ test('.like()', t => {
 		return assertions.like({xc: [circular, 'c']}, {xc: [circular, 'd']});
 	});
 
-	failsWith(t, () => assertions.like({a: 'a'}, {}), {
+	failsWith(t, () => assertions.like({a: 'a'}, Object.defineProperties({}, {ignored: {}})), {
 		assertion: 'like',
 		message: '`t.like()` selector must be a non-empty object',
 		values: [{label: 'Called with:', formatted: '{}'}],
@@ -732,6 +732,15 @@ test('.like()', t => {
 		values: [{label: 'Called with:', formatted: '\'bar\''}],
 	});
 
+	passes(t, () => {
+		const specimen = {[Symbol.toStringTag]: 'Custom', extra: true};
+		const selector = Object.defineProperties(
+			{[Symbol.toStringTag]: 'Custom'},
+			{ignored: {value: true}},
+		);
+		return assertions.like(specimen, selector);
+	});
+
 	failsWith(t, () => {
 		const likePattern = {
 			a: 'a',