Overlay unit tests

lib/ios/RNNOverlayManager.h

 - (void)showOverlay:(UIViewController*)viewController;
 - (void)dismissOverlay:(UIViewController*)viewController;
 
+@property (nonatomic, retain) NSMutableArray* overlayWindows;
+
 @end

lib/ios/RNNOverlayManager.m

 #import "RNNOverlayManager.h"
 #import "RNNOverlayWindow.h"
 
-@implementation RNNOverlayManager {
-	NSMutableArray* _overlayWindows;
-}
+@implementation RNNOverlayManager
 
 - (instancetype)init {
 	self = [super init];

lib/ios/ReactNativeNavigation.xcodeproj/project.pbxproj

 		50451D0A2042E20600695F00 /* RNNTransitionsOptions.m in Sources */ = {isa = PBXBuildFile; fileRef = 50451D082042E20600695F00 /* RNNTransitionsOptions.m */; };
 		50451D0D2042F70900695F00 /* RNNTransition.h in Headers */ = {isa = PBXBuildFile; fileRef = 50451D0B2042F70900695F00 /* RNNTransition.h */; };
 		50451D0E2042F70900695F00 /* RNNTransition.m in Sources */ = {isa = PBXBuildFile; fileRef = 50451D0C2042F70900695F00 /* RNNTransition.m */; };
+		504753782109C13C00FFFBE6 /* RNNOverlayManagerTest.m in Sources */ = {isa = PBXBuildFile; fileRef = 504753772109C13C00FFFBE6 /* RNNOverlayManagerTest.m */; };
 		5048862D20BE976D000908DE /* RNNLayoutOptions.h in Headers */ = {isa = PBXBuildFile; fileRef = 5048862B20BE976D000908DE /* RNNLayoutOptions.h */; };
 		5048862E20BE976D000908DE /* RNNLayoutOptions.m in Sources */ = {isa = PBXBuildFile; fileRef = 5048862C20BE976D000908DE /* RNNLayoutOptions.m */; };
 		504AFE651FFE53070076E904 /* RNNOptions.m in Sources */ = {isa = PBXBuildFile; fileRef = 504AFE631FFE53070076E904 /* RNNOptions.m */; };
 		50451D082042E20600695F00 /* RNNTransitionsOptions.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = RNNTransitionsOptions.m; sourceTree = "<group>"; };
 		50451D0B2042F70900695F00 /* RNNTransition.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = RNNTransition.h; sourceTree = "<group>"; };
 		50451D0C2042F70900695F00 /* RNNTransition.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = RNNTransition.m; sourceTree = "<group>"; };
+		504753772109C13C00FFFBE6 /* RNNOverlayManagerTest.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RNNOverlayManagerTest.m; sourceTree = "<group>"; };
 		5048862B20BE976D000908DE /* RNNLayoutOptions.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = RNNLayoutOptions.h; sourceTree = "<group>"; };
 		5048862C20BE976D000908DE /* RNNLayoutOptions.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = RNNLayoutOptions.m; sourceTree = "<group>"; };
 		504AFE621FFE53070076E904 /* RNNOptions.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = RNNOptions.h; sourceTree = "<group>"; };
 				7B49FEC81E95098500DEB3EA /* RNNModalManagerTest.m */,
 				7B49FEC91E95098500DEB3EA /* RNNCommandsHandlerTest.m */,
 				7B49FECA1E95098500DEB3EA /* RNNNavigationStackManagerTest.m */,
+				504753772109C13C00FFFBE6 /* RNNOverlayManagerTest.m */,
 				7B49FEBF1E95090800DEB3EA /* Info.plist */,
 				E83BAD671F2734B500A9F3DD /* RNNNavigationOptionsTest.m */,
 				E83BAD781F27416B00A9F3DD /* RNNRootViewControllerTest.m */,
 			buildActionMask = 2147483647;
 			files = (
 				E83BAD7C1F27643000A9F3DD /* RNNTestRootViewCreator.m in Sources */,
+				504753782109C13C00FFFBE6 /* RNNOverlayManagerTest.m in Sources */,
 				7B49FECE1E95098500DEB3EA /* RNNCommandsHandlerTest.m in Sources */,
 				E83BAD681F2734B500A9F3DD /* RNNNavigationOptionsTest.m in Sources */,
 				7B49FECF1E95098500DEB3EA /* RNNNavigationStackManagerTest.m in Sources */,

lib/ios/ReactNativeNavigationTests/RNNOverlayManagerTest.m

+#import <XCTest/XCTest.h>
+#import "RNNOverlayManager.h"
+
+@interface RNNOverlayManagerTest : XCTestCase
+
+@property (nonatomic, retain) RNNOverlayManager* overlayManager;
+@property (nonatomic, retain) UIViewController* overlayVC;
+
+@end
+
+@implementation RNNOverlayManagerTest
+
+- (void)setUp {
+    [super setUp];
+	_overlayManager = [RNNOverlayManager new];
+	_overlayVC = [UIViewController new];
+}
+
+
+- (void)testShowOverlayShouldAddWindowWithVCAsRoot {
+	[_overlayManager showOverlay:_overlayVC];
+	UIWindow* window = _overlayManager.overlayWindows.lastObject;
+	XCTAssertTrue([window.rootViewController isEqual:_overlayVC]);
+}
+
+- (void)testShowOverlayShouldAddVisibleWindow {
+	[_overlayManager showOverlay:_overlayVC];
+	UIWindow* window = _overlayManager.overlayWindows.lastObject;
+	XCTAssertTrue(window.windowLevel == UIWindowLevelNormal);
+	XCTAssertFalse(window.hidden);
+}
+
+- (void)testDismissOverlayShouldCleanWindowRootVC {
+	[_overlayManager showOverlay:_overlayVC];
+	UIWindow* window = _overlayManager.overlayWindows.lastObject;
+	[_overlayManager dismissOverlay:_overlayVC];
+	XCTAssertNil(window.rootViewController);
+}
+
+- (void)testDismissOverlayShouldHideWindow {
+	[_overlayManager showOverlay:_overlayVC];
+	UIWindow* window = _overlayManager.overlayWindows.lastObject;
+	[_overlayManager dismissOverlay:_overlayVC];
+	XCTAssertTrue(window.hidden);
+}
+
+- (void)testDismissOverlayShouldRemoveOverlayWindow {
+	[_overlayManager showOverlay:_overlayVC];
+	UIWindow* window = _overlayManager.overlayWindows.lastObject;
+	[_overlayManager dismissOverlay:_overlayVC];
+	XCTAssertFalse([_overlayManager.overlayWindows containsObject:window]);
+}
+
+@end