feat: Make options.runOnly more forgiving about plurality

BREAKING CHANGE: Incorrect use of runOnly now throws errors

doc/API.md

@@ -376,6 +376,14 @@ Additionally, there are a number or properties that allow configuration of diffe
 	}
 	```
 
+  Alternatively, runOnly can be passed an array of tags:
+
+  ```javascript
+  {
+    runOnly: ["wcag2a", "wcag2aa"]
+  }
+  ```
+
 2. Run only a specified list of Rules
 
 	If you only want to run certain rules, specify options as:

lib/core/base/audit.js

@@ -142,7 +142,7 @@ Audit.prototype.addCheck = function (spec) {
  */
 Audit.prototype.run = function (context, options, resolve, reject) {
 	'use strict';
-	this.validateOptions(options);
+	this.normalizeOptions(options);
 
 	axe._selectCache = [];
 	var q = axe.utils.queue();
@@ -220,42 +220,53 @@ Audit.prototype.getRule = function (ruleId) {
  * @param  {Object} options  Options object
  * @return {Object}          Validated options object
  */
-Audit.prototype.validateOptions = function (options) {
+Audit.prototype.normalizeOptions = function (options) {
+	/* eslint max-statements: ["error", 22] */
 	'use strict';
 	var audit = this;
 
 	// Validate runOnly
 	if (typeof options.runOnly === 'object') {
-		var only = options.runOnly;
+		if (Array.isArray(options.runOnly)) {
+			options.runOnly = {
+				type: 'tag',
+				values: options.runOnly
+			};
+		}
+		const only = options.runOnly;
+		if (only.value && !only.values) {
+			only.values = only.value;
+			delete only.value;
+		}
+
+		if (!Array.isArray(only.values) || only.values.length === 0) {
+			throw new Error('runOnly.values must be a non-empty array');
+		}
 
 		// Check if every value in options.runOnly is a known rule ID
-		if (only.type === 'rule' && Array.isArray(only.value)) {
-			only.value.forEach(function (ruleId) {
+		if (['rule', 'rules'].includes(only.type)) {
+			only.type = 'rule';
+			only.values.forEach(function (ruleId) {
 				if (!audit.getRule(ruleId)) {
 					throw new Error('unknown rule `' + ruleId +  '` in options.runOnly');
 				}
 			});
 
 		// Validate 'tags' (e.g. anything not 'rule')
-		} else if (Array.isArray(only.value) && only.value.length > 0) {
-			var tags = [].concat(only.value);
-
-			audit.rules.forEach(function (rule) {
-				var tagPos, i, l;
-				if (!tags) {
-					return;
-				}
-				// Remove any known tag
-				for (i = 0, l = rule.tags.length; i < l; i++) {
-					tagPos = tags.indexOf(rule.tags[i]);
-					if (tagPos !== -1) {
-						tags.splice(tagPos, 1);
-					}
-				}
-			});
-			if (tags.length !== 0) {
-				throw new Error('could not find tags `' + tags.join('`, `') + '`');
+		} else if (['tag', 'tags', undefined].includes(only.type)) {
+			only.type = 'tag';
+			const unmatchedTags = audit.rules.reduce((unmatchedTags, rule) => {
+				return (unmatchedTags.length
+					? unmatchedTags.filter(tag => !rule.tags.includes(tag))
+					: unmatchedTags
+				);
+			}, only.values);
+
+			if (unmatchedTags.length !== 0) {
+				throw new Error('Could not find tags `' + unmatchedTags.join('`, `') + '`');
 			}
+		} else {
+			throw new Error(`Unknown runOnly type '${only.type}'`);
 		}
 	}
 

test/core/base/audit.js

@@ -32,20 +32,24 @@ describe('Audit', function () {
 	var mockRules = [{
 		id: 'positive1',
 		selector: 'input',
+		tags: ['positive'],
 		any: [{
 			id: 'positive1-check1',
 		}]
 	}, {
 		id: 'positive2',
 		selector: '#monkeys',
+		tags: ['positive'],
 		any: ['positive2-check1']
 	}, {
 		id: 'negative1',
 		selector: 'div',
+		tags: ['negative'],
 		none: ['negative1-check1']
 	}, {
 		id: 'positive3',
 		selector: 'blink',
+		tags: ['positive'],
 		any: ['positive3-check1']
 	}];
 
@@ -621,14 +625,14 @@ describe('Audit', function () {
 			}, isNotCalled);
 		});
 
-		it('should run audit.validateOptions to ensure valid input', function () {
+		it('should run audit.normalizeOptions to ensure valid input', function () {
 			fixture.innerHTML = '<input type="text" aria-label="monkeys">' +
 				'<div id="monkeys">bananas</div>' +
 				'<input aria-labelledby="monkeys" type="text">' +
 				'<blink>FAIL ME</blink>';
 			var checked = 'options not validated';
 
-			a.validateOptions = function () {
+			a.normalizeOptions = function () {
 				checked = 'options validated';
 			};
 
@@ -687,46 +691,127 @@ describe('Audit', function () {
 		});
 	});
 
-	describe('Audit#validateOptions', function () {
+	describe('Audit#normalizeOptions', function () {
 
 		it('returns the options object when it is valid', function () {
 			var opt = {
 				runOnly: {
 					type: 'rule',
-					value: ['positive1', 'positive2']
+					values: ['positive1', 'positive2']
 				},
 				rules: {
 					negative1: { enabled: false }
 				}
 			};
-			assert(a.validateOptions(opt), opt);
+			assert(a.normalizeOptions(opt), opt);
+		});
+
+		it('allows `value` as alternative to `values`', function () {
+			var opt = {
+				runOnly: {
+					type: 'rule',
+					value: ['positive1', 'positive2']
+				}
+			};
+			var out = a.normalizeOptions(opt)
+			assert.deepEqual(out.runOnly.values, ['positive1', 'positive2']);
+			assert.isUndefined(out.runOnly.value);
+		});
+
+		it('allows type: rules as an alternative to type: rule', function () {
+			var opt = {
+				runOnly: {
+					type: 'rules',
+					values: ['positive1', 'positive2']
+				}
+			};
+			assert(a.normalizeOptions(opt).runOnly.type, 'rule');
+		});
+
+		it('allows type: tags as an alternative to type: tag', function () {
+			var opt = {
+				runOnly: {
+					type: 'tags',
+					values: ['positive']
+				}
+			};
+			assert(a.normalizeOptions(opt).runOnly.type, 'tag');
+		});
+
+		it('allows type: undefined as an alternative to type: tag', function () {
+			var opt = {
+				runOnly: {
+					values: ['positive']
+				}
+			};
+			assert(a.normalizeOptions(opt).runOnly.type, 'tag');
+		});
+
+		it('allows runOnly as an array as an alternative to type: tag', function () {
+			var opt = { runOnly: ['positive', 'negative'] };
+			var out = a.normalizeOptions(opt);
+			assert(out.runOnly.type, 'tag');
+			assert.deepEqual(out.runOnly.values, ['positive', 'negative']);
+		});
+
+		it('throws an error runOnly.values not an array', function () {
+			assert.throws(function () {
+				a.normalizeOptions({
+					runOnly: {
+						type: 'rule',
+						values: { badProp: 'badValue' }
+					}
+				});
+			});
+		});
+
+		it('throws an error runOnly.values an empty', function () {
+			assert.throws(function () {
+				a.normalizeOptions({
+					runOnly: {
+						type: 'rule',
+						values: []
+					}
+				});
+			});
+		});
+
+		it('throws an error runOnly.type is unknown', function () {
+			assert.throws(function () {
+				a.normalizeOptions({
+					runOnly: {
+						type: 'something-else',
+						values: ['wcag2aa']
+					}
+				});
+			});
 		});
 
 		it('throws an error when option.runOnly has an unknown rule', function () {
 			assert.throws(function () {
-				a.validateOptions({
+				a.normalizeOptions({
 					runOnly: {
 						type: 'rule',
-						value: ['frakeRule']
+						values: ['frakeRule']
 					}
 				});
 			});
 		});
 
 		it('throws an error when option.runOnly has an unknown tag', function () {
 			assert.throws(function () {
-				a.validateOptions({
+				a.normalizeOptions({
 					runOnly: {
 						type: 'tags',
-						value: ['fakeTag']
+						values: ['fakeTag']
 					}
 				});
 			});
 		});
 
 		it('throws an error when option.rules has an unknown rule', function () {
 			assert.throws(function () {
-				a.validateOptions({
+				a.normalizeOptions({
 					rules: {
 						fakeRule: { enabled: false}
 					}