Add always option to consistent-output rule

docs/rules/consistent-output.md

@@ -56,6 +56,13 @@ new RuleTester().run('example-rule', rule, {
 
 ```
 
+## Options
+
+This rule takes an optional string enum option with one of the following values:
+
+* `"consistent"` - (default) if any invalid test cases have output assertions, then all invalid test cases must have output assertions
+* `"always"` - always require invalid test cases to have output assertions
+
 ## When Not To Use It
 
 If you're not writing fixable rules, or you want to write test cases without output assertions, do not enable this rule.

lib/rules/consistent-output.js

@@ -20,13 +20,19 @@ module.exports = {
     },
     type: 'suggestion',
     fixable: null, // or "code" or "whitespace"
-    schema: [],
+    schema: [
+      {
+        type: 'string',
+        enum: ['always', 'consistent'],
+      },
+    ],
   },
 
   create (context) {
     // ----------------------------------------------------------------------
     // Public
     // ----------------------------------------------------------------------
+    const always = context.options[0] && context.options[0] === 'always';
 
     return {
       Program (ast) {
@@ -35,7 +41,10 @@ module.exports = {
           const casesWithoutOutput = readableCases
             .filter(testCase => testCase.properties.map(utils.getKeyName).indexOf('output') === -1);
 
-          if (casesWithoutOutput.length < readableCases.length) {
+          if (
+            (casesWithoutOutput.length < readableCases.length) ||
+            (always && casesWithoutOutput.length > 0)
+          ) {
             casesWithoutOutput.forEach(testCase => {
               context.report({
                 node: testCase,

tests/lib/rules/consistent-output.js

@@ -53,6 +53,21 @@ ruleTester.run('consistent-output', rule, {
         ]
       });
     `,
+    {
+      code: `
+        new RuleTester().run('foo', bar, {
+          valid: [],
+          invalid: [
+            {
+              code: 'foo',
+              output: 'baz',
+              errors: ['bar']
+            },
+          ]
+        });
+      `,
+      options: ['always'],
+    },
   ],
 
   invalid: [
@@ -79,5 +94,20 @@ ruleTester.run('consistent-output', rule, {
       `,
       errors: [ERROR, ERROR],
     },
+    {
+      code: `
+        new RuleTester().run('foo', bar, {
+          valid: [],
+          invalid: [
+            {
+              code: 'foo',
+              errors: ['bar'],
+            },
+          ]
+        });
+      `,
+      options: ['always'],
+      errors: [ERROR],
+    },
   ],
 });