Add support for using PF_Twitter without a linking or logging into a Parse account

ParseTwitterUtils/PF_Twitter.h

@@ -21,6 +21,15 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @interface PF_Twitter : NSObject
 
+/**
+ Initializes an instance of `PF_Twitter` configured to access device Twitter accounts with Accounts.framework,
+ and remote access to Twitter accounts - and, if no accounts are found locally - through a built-in webview.
+
+ After setting `consumerKey` and `consumerSecret`, authorization to Twitter accounts can be requested with
+`authorizeInBackground`, and then revoked with its opposite, `deauthorizeInBackground`.
+ */
+- (instancetype)init;
+
 /**
  Consumer key of the application that is used to authorize with Twitter.
  */
@@ -59,6 +68,14 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (BFTask *)authorizeInBackground;
 
+/**
+ Invalidates an OAuth token for the current user, if the Twitter user has granted permission to the
+ current application.
+
+ @return The task, that encapsulates the work being done.
+ */
+- (BFTask *)deauthorizeInBackground;
+
 /**
  Displays an auth dialog and populates the authToken, authTokenSecret, userId, and screenName properties
  if the Twitter user grants permission to the application.

ParseTwitterUtils/PF_Twitter.m

@@ -92,6 +92,28 @@ - (BFTask *)authorizeInBackground {
         return source.task;
     }];
 }
+- (BFTask *)deauthorizeInBackground {
+    if (self.consumerKey.length == 0 || self.consumerSecret.length == 0) {
+        //TODO: (nlutsenko) This doesn't look right, maybe we should add additional error code?
+        return [BFTask taskWithError:[NSError errorWithDomain:PFParseErrorDomain code:1 userInfo:nil]];
+    }
+
+    return [[self _performDeauthAsync] pftw_continueAsyncWithBlock:^id(BFTask *task) {
+        BFTaskCompletionSource *source = [BFTaskCompletionSource taskCompletionSource];
+        if (task.cancelled) {
+            [source cancel];
+        } else if (!task.error && !task.result) {
+            source.result = nil;
+        } else if (task.error) {
+            [source trySetError:task.error];
+        } else if (task.result) {
+            [self setLoginResultValues:nil];
+
+            [source trySetResult:task.result];
+        }
+        return source.task;
+    }];
+}
 
 - (void)authorizeWithSuccess:(void (^)(void))success
                      failure:(void (^)(NSError *error))failure
@@ -428,6 +450,26 @@ - (BFTask *)_performWebViewAuthAsync {
     return source.task;
 }
 
+- (BFTask *)_performDeauthAsync {
+    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
+    request.URL = [NSURL URLWithString:@"https://api.twitter.com/oauth2/invalidate_token"];
+    request.HTTPMethod = @"POST";
+
+    [self signRequest:request];
+
+    BFTaskCompletionSource *taskCompletionSource = [BFTaskCompletionSource taskCompletionSource];
+
+    [[self.urlSession dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
+        if (error) {
+            [taskCompletionSource trySetError:error];
+        } else {
+            [taskCompletionSource trySetResult:data];
+        }
+    }] resume];
+
+    return taskCompletionSource.task;
+}
+
 ///--------------------------------------
 #pragma mark - Sign Request
 ///--------------------------------------

Tests/Unit/TwitterTests.m

@@ -622,4 +622,62 @@ - (void)testAuthorizeWithoutLocalAccountAndNetworkSuccess {
     OCMVerifyAll(mockedURLSession);
 }
 
+- (void)testDeauthorizeLoggedOutAccount {
+    id store = PFStrictClassMock([ACAccountStore class]);
+    NSURLSession *session = PFStrictClassMock([NSURLSession class]);
+    id mockedDialog = PFStrictProtocolMock(@protocol(PFOAuth1FlowDialogInterface));
+    PF_Twitter *twitter = [[PF_Twitter alloc] initWithAccountStore:store urlSession:session dialogClass:mockedDialog];
+
+    XCTestExpectation *expectation = [self currentSelectorTestExpectation];
+    [[twitter authorizeInBackground] continueWithBlock:^id(BFTask *task) {
+        NSError *error = task.error;
+        XCTAssertNotNil(error);
+        XCTAssertEqualObjects(error.domain, PFParseErrorDomain);
+        XCTAssertEqual(error.code, 1);
+        [expectation fulfill];
+        return nil;
+    }];
+    [self waitForTestExpectations];
+}
+
+- (void)testDeauthorizeLoggedInAccount {
+    id mockedStore = PFStrictClassMock([ACAccountStore class]);
+    id mockedURLSession = PFStrictClassMock([NSURLSession class]);
+    id mockedOperationQueue = PFStrictClassMock([NSOperationQueue class]);
+
+    id mockedDialog = PFStrictProtocolMock(@protocol(PFOAuth1FlowDialogInterface));
+    PF_Twitter *twitter = [[PF_Twitter alloc] initWithAccountStore:mockedStore urlSession:mockedURLSession dialogClass:mockedDialog];
+    twitter.consumerKey = @"consumer_key";
+    twitter.consumerSecret = @"consumer_secret";
+    twitter.authToken = @"auth_token";
+    twitter.authTokenSecret = @"auth_token_secret";
+    twitter.userId = @"user_id";
+    twitter.screenName = @"screen_name";
+
+    __block NSURLSessionDataTaskCompletionHandler completionHandler = nil;
+    [OCMStub([mockedURLSession dataTaskWithRequest:[OCMArg checkWithBlock:^BOOL(id obj) {
+        NSURLRequest *request = obj;
+        return [request.URL.lastPathComponent isEqualToString:@"invalidate_token"];
+    }] completionHandler:[OCMArg checkWithBlock:^BOOL(id obj) {
+        completionHandler = obj;
+        return (obj != nil);
+    }]]).andDo(^(NSInvocation *invocation) {
+        completionHandler([NSData data], nil, nil);
+    }) andReturn:[OCMockObject niceMockForClass:[NSURLSessionDataTask class]]];
+
+    XCTestExpectation *expectation = [self currentSelectorTestExpectation];
+    [[twitter deauthorizeInBackground] continueWithBlock:^id(BFTask *task) {
+        NSError *error = task.error;
+        XCTAssertNil(error);
+        XCTAssertNotNil(task.result);
+
+        XCTAssertNil(twitter.authToken);
+        XCTAssertNil(twitter.authTokenSecret);
+
+        [expectation fulfill];
+        return nil;
+    }];
+    [self waitForTestExpectations];
+}
+
 @end