Checks for nil applicationId and clientKey

Parse/Parse.m

@@ -55,8 +55,9 @@ + (void)initialize {
 ///--------------------------------------
 
 + (void)setApplicationId:(NSString *)applicationId clientKey:(NSString *)clientKey {
-    // TODO: (nlutsenko) Add assert and unit test here that checks applicationId, clientKey not being nil.
-
+    PFConsistencyAssert([applicationId length], @"'applicationId' should not be nil.");
+    PFConsistencyAssert([clientKey length], @"'clientKey' should not be nil.");
+
     // Setup new manager first, so it's 100% ready whenever someone sends a request for anything.
     ParseManager *manager = [[ParseManager alloc] initWithApplicationId:applicationId clientKey:clientKey];
     [manager configureWithApplicationGroupIdentifier:applicationGroupIdentifier_

Tests/Unit/ParseSetupUnitTests.m

@@ -45,4 +45,12 @@ - (void)testInitializeWithLDSAfterInitializeShouldThrowException {
     [Parse setApplicationId:@"a" clientKey:@"b"];
     PFAssertThrowsInconsistencyException([Parse enableLocalDatastore]);
 }
+
+- (void)testInitializeWithNilApplicationIdNilClientKeyShouldThrowException {
+    NSString *yolo = nil;
+    PFAssertThrowsInconsistencyException([Parse setApplicationId:yolo clientKey:yolo]);
+    PFAssertThrowsInconsistencyException([Parse setApplicationId:yolo clientKey:@"a"]);
+    PFAssertThrowsInconsistencyException([Parse setApplicationId:@"a" clientKey:yolo]);
+}
+
 @end