fix: Do not treat an array of config values as a sub-command config section

src/config.js

@@ -32,14 +32,17 @@ export function applyConfigToArgv({
 }: ApplyConfigToArgvParams): Object {
   let newArgv = {...argv};
 
-  for (const option in configObject) {
+  for (const option of Object.keys(configObject)) {
     if (camelCase(option) !== option) {
       throw new UsageError(
         `The config option "${option}" must be ` +
         `specified in camel case: "${camelCase(option)}"`);
     }
 
-    if (typeof options[option] === 'object' &&
+    // A config option cannot be a sub-command config
+    // object if it is an array.
+    if (!Array.isArray(configObject[option]) &&
+      typeof options[option] === 'object' &&
       typeof configObject[option] === 'object') {
       // Descend into the nested configuration for a sub-command.
       newArgv = applyConfigToArgv({

src/program.js

@@ -401,7 +401,7 @@ Example: $0 --help run.
                   'run against multiple targets.',
         default: 'firefox-desktop',
         demand: false,
-        type: 'string',
+        type: 'array',
       },
       'firefox': {
         alias: ['f', 'firefox-binary'],
@@ -447,15 +447,15 @@ Example: $0 --help run.
                   'preference.',
         demand: false,
         requiresArg: true,
-        type: 'string',
+        type: 'array',
         coerce: coerceCLICustomPreference,
       },
       'start-url': {
         alias: ['u', 'url'],
         describe: 'Launch firefox at specified page',
         demand: false,
         requiresArg: true,
-        type: 'string',
+        type: 'array',
       },
       'browser-console': {
         alias: ['bc'],

tests/unit/test.config.js

@@ -296,6 +296,30 @@ describe('config', () => {
       assert.strictEqual(argv.ignoreFiles, configObject.ignoreFiles);
     });
 
+    it('does not mistake an array config values for a sub-command',
+       () => {
+         const params = makeArgv({
+           userCmd: ['fakecommand'],
+           globalOpt: {
+             pref: {
+               demand: false,
+               type: 'string',
+             },
+           },
+         });
+
+         const configObject = {
+           pref: ['pref1=true', 'pref2=false'],
+         };
+
+         // TODO: expect a raised exception array is not a string
+         assert.throws(
+           () => applyConf({...params, configObject}),
+           UsageError,
+           'type of "pref" incorrectly as "array" (expected type "string")'
+         );
+       });
+
     it('uses CLI option over undefined configured option and default', () => {
       const cmdLineSrcDir = '/user/specified/source/dir/';
       const params = makeArgv({

tests/unit/test.program.js

@@ -449,7 +449,7 @@ describe('program.main', () => {
       .then(() => {
         sinon.assert.calledWithMatch(
           fakeCommands.run,
-          {startUrl: 'www.example.com'}
+          {startUrl: ['www.example.com']}
         );
       });
   });