Reapply "chore: cleanup references of --opts (#5402)" (#5404) (#5476)

Author: mark-wiemer

.wallaby.js

@@ -16,7 +16,6 @@ module.exports = () => {
         instrument: false
       },
       'package.json',
-      'test/opts/mocha.opts',
       'mocharc.yml',
       '!lib/browser/growl.js'
     ],

lib/cli/run.js

@@ -169,11 +169,15 @@ exports.builder = yargs =>
         group: GROUPS.RULES
       },
       'list-interfaces': {
-        conflicts: Array.from(ONE_AND_DONE_ARGS).filter(arg => arg !== "list-interfaces"),
+        conflicts: Array.from(ONE_AND_DONE_ARGS).filter(
+          arg => arg !== 'list-interfaces'
+        ),
         description: 'List built-in user interfaces & exit'
       },
       'list-reporters': {
-        conflicts: Array.from(ONE_AND_DONE_ARGS).filter(arg => arg !== "list-reporters"),
+        conflicts: Array.from(ONE_AND_DONE_ARGS).filter(
+          arg => arg !== 'list-reporters'
+        ),
         description: 'List built-in reporters & exit'
       },
       'no-colors': {
@@ -196,7 +200,8 @@ exports.builder = yargs =>
         group: GROUPS.RULES
       },
       'posix-exit-codes': {
-        description: 'Use POSIX and UNIX shell exit codes as Mocha\'s return value',
+        description:
+          "Use POSIX and UNIX shell exit codes as Mocha's return value",
         group: GROUPS.RULES
       },
       recursive: {
@@ -342,13 +347,6 @@ exports.builder = yargs =>
         );
       }
 
-      if (argv.opts) {
-        throw createUnsupportedError(
-          `--opts: configuring Mocha via 'mocha.opts' is DEPRECATED and no longer supported.
-          Please use a configuration file instead.`
-        );
-      }
-
       return true;
     })
     .middleware(async (argv, yargs) => {