Added tests and changed NULL to nil

Branch-TestBed/Branch-SDK-Tests/BNCAPIServerTest.m

@@ -11,6 +11,7 @@
 #import "BNCSystemObserver.h"
 #import "BNCConfig.h"
 #import "BranchConstants.h"
+#import "Branch.h"
 
 @interface BNCAPIServerTest : XCTestCase
 
@@ -370,4 +371,42 @@ - (void)testValidationServiceURL_EUTracking {
     XCTAssertTrue([url hasPrefix:expectedUrlPrefix]);
 }
 
+- (void)testDefaultAPIURL {
+    BNCServerAPI *serverAPI = [BNCServerAPI new];
+    XCTAssertNil(serverAPI.customAPIURL);
+
+    NSString *storedUrl = [[BNCServerAPI sharedInstance] installServiceURL];
+    NSString *expectedUrl = [BNC_API_URL stringByAppendingString: @"/v1/install"];
+    XCTAssertEqualObjects(storedUrl, expectedUrl);
+}
+
+- (void)testSetAPIURL_Example {
+    NSString *url = @"https://www.example.com";
+    [Branch setAPIUrl:url];
+
+    NSString *storedUrl = [[BNCServerAPI sharedInstance] installServiceURL];
+    NSString *expectedUrl = [url stringByAppendingString: @"/v1/install"];
+    XCTAssertEqualObjects(storedUrl, expectedUrl);
+
+    [Branch setAPIUrl:BNC_API_URL];
+}
+
+- (void)testSetAPIURL_InvalidHttp {
+    NSString *url = @"Invalid://www.example.com";
+    [Branch setAPIUrl:url];
+
+    NSString *storedUrl = [[BNCServerAPI sharedInstance] installServiceURL];
+    NSString *expectedUrl = [BNC_API_URL stringByAppendingString: @"/v1/install"];
+    XCTAssertEqualObjects(storedUrl, expectedUrl);
+}
+
+- (void)testSetAPIURL_InvalidEmpty {
+    NSString *url = @"";
+    [Branch setAPIUrl:url];
+
+    NSString *storedUrl = [[BNCServerAPI sharedInstance] installServiceURL];
+    NSString *expectedUrl = [BNC_API_URL stringByAppendingString: @"/v1/install"];
+    XCTAssertEqualObjects(storedUrl, expectedUrl);
+}
+
 @end

BranchSDK/BNCServerAPI.m

@@ -30,7 +30,7 @@ - (instancetype)init {
         self.useTrackingDomain = NO;
         self.useEUServers = NO;
         self.automaticallyEnableTrackingDomain = YES;
-        self.customAPIURL = NULL;
+        self.customAPIURL = nil;
     }
     return self;
 }