improve error handling

atom/browser/api/atom_api_system_preferences_mac.mm

@@ -146,13 +146,17 @@ v8::Local<v8::Value> SystemPreferences::GetUserDefault(
 
 void SystemPreferences::RegisterDefaults(mate::Arguments* args) {
   base::DictionaryValue value;
-  args->GetNext(&value);
   
-  @try {
-    NSDictionary* dict = DictionaryValueToNSDictionary(value);
-    [[NSUserDefaults standardUserDefaults] registerDefaults:dict];
-  } @catch (NSException* exception) {
+  if(!args->GetNext(&value)) {
     args->ThrowError("Invalid userDefault data provided");
+  } else {
+    args->GetNext(&value);
+    @try {
+      NSDictionary* dict = DictionaryValueToNSDictionary(value);
+      [[NSUserDefaults standardUserDefaults] registerDefaults:dict];
+    } @catch (NSException* exception) {
+      args->ThrowError("Invalid userDefault data provided");
+    }
   }
 }
 

spec/api-system-preferences-spec.js

@@ -35,18 +35,20 @@ describe('systemPreferences module', () => {
     })
   })
 
-  describe.only('systemPreferences.registerDefaults(defaults)', () => {
+  describe('systemPreferences.registerDefaults(defaults)', () => {
     before(function () {
       if (process.platform !== 'darwin') this.skip()
     })
 
     it('registers defaults', () => {
+      // to pass into registerDefaults
       const defaultsDict = {
         'one': 'ONE',
         'two': 2,
         'three': [1, 2, 3]
       }
 
+      // to test type
       const defaultsMap = [
         { key: 'one', type: 'string', value: 'ONE' },
         { key: 'two', value: 2, type: 'integer' },
@@ -63,16 +65,21 @@ describe('systemPreferences module', () => {
     })
 
     it('throws when bad defaults are passed', () => {
-      const badDefaults1 = { 'one': null }
-      //const badDefaults1 = { 'one': null }
+      const badDefaults1 = { 'one': null } // catches null values
+      const badDefaults2 = 1 // argument must be a dictionary
+      const badDefaults3 = null // argument can't be null
 
       assert.throws(() => {
         systemPreferences.registerDefaults(badDefaults1)
       }, 'Invalid userDefault data provided')
-      //
-      // assert.throws(() => {
-      //   systemPreferences.registerDefaults(badDefaults1)
-      // }, 'Invalid userDefault data provided')
+
+      assert.throws(() => {
+        systemPreferences.registerDefaults(badDefaults2)
+      }, 'Invalid userDefault data provided')
+
+      assert.throws(() => {
+        systemPreferences.registerDefaults(badDefaults3)
+      }, 'Invalid userDefault data provided')
     })
   })