Add Null Check to Handle the Scenario Where the Scope Value is null

components/apimgt/org.wso2.carbon.apimgt.gateway/src/main/java/org/wso2/carbon/apimgt/gateway/mediators/oauth/client/OAuthClient.java

@@ -163,8 +163,13 @@ private static TokenResponse getTokenResponse(CloseableHttpResponse response)
             if (jsonResponse.containsKey("refresh_token")) {
                 tokenResponse.setRefreshToken((String) jsonResponse.get("refresh_token"));
             }
-            if (jsonResponse.containsKey("scope")) {
-                Set<String> scopeSet = Stream.of(jsonResponse.get("scope").toString().trim()
+            Object scopes = jsonResponse.get("scope");
+            /* The scopes object will be null in the following scenarios
+                1. The scope key is not present in the jsonResponse object
+                2. The value of the scope key is null (Example: "scope": null)
+            */
+            if (scopes != null) {
+                Set<String> scopeSet = Stream.of(scopes.toString().trim()
                         .split("\\s*,\\s*")).collect(Collectors.toSet());
                 tokenResponse.setScope(scopeSet);
             }

components/apimgt/org.wso2.carbon.apimgt.gateway/src/test/java/org/wso2/carbon/apimgt/gateway/handlers/security/oauth/OAuthClientTest.java

@@ -0,0 +1,223 @@
+/*
+ * Copyright (c) 2024, WSO2 LLC. (http://www.wso2.com) All Rights Reserved.
+ *
+ * WSO2 LLC. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.wso2.carbon.apimgt.gateway.handlers.security.oauth;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.http.HttpStatus;
+import org.apache.http.StatusLine;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpPost;
+import org.apache.http.entity.StringEntity;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.json.simple.parser.ParseException;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.powermock.core.classloader.annotations.PrepareForTest;
+import org.powermock.modules.junit4.PowerMockRunner;
+import org.wso2.carbon.apimgt.api.APIManagementException;
+import org.wso2.carbon.apimgt.gateway.internal.ServiceReferenceHolder;
+import org.wso2.carbon.apimgt.gateway.mediators.oauth.OAuthTokenGenerator;
+import org.wso2.carbon.apimgt.gateway.mediators.oauth.TokenCache;
+import org.wso2.carbon.apimgt.gateway.mediators.oauth.client.OAuthClient;
+import org.wso2.carbon.apimgt.gateway.mediators.oauth.client.TokenResponse;
+import org.wso2.carbon.apimgt.impl.utils.APIUtil;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.mockito.Mockito.when;
+import static org.mockito.Mockito.any;
+import static org.mockito.Mockito.anyInt;
+import static org.mockito.Mockito.anyString;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.powermock.api.mockito.PowerMockito.mockStatic;
+
+@RunWith(PowerMockRunner.class)
+@PrepareForTest({OAuthClient.class, OAuthTokenGenerator.class, TokenCache.class, ServiceReferenceHolder.class,
+        APIUtil.class})
+public class OAuthClientTest {
+    @Mock
+    private CloseableHttpClient mockHttpClient;
+
+    @Mock
+    private CloseableHttpResponse mockResponse;
+
+    @Mock
+    private StatusLine mockStatusLine;
+
+    private static final String TOKEN_URL = "https://example.com/token";
+    private static final String CLIENT_ID = "testClientId";
+    private static final String CLIENT_SECRET = "testClientSecret";
+    private static final String USERNAME = "testUser";
+    private static final char[] PASSWORD = "testPassword".toCharArray();
+    private static final String GRANT_TYPE = "PASSWORD";
+    private static final String ACCESS_TOKEN_FIELD = "access_token";
+    private static final String ACCESS_TOKEN_VALUE = "testAccessToken";
+    private static final String REFRESH_TOKEN_FIELD = "refresh_token";
+    private static final String REFRESH_TOKEN_VALUE = "testRefreshToken";
+    private static final String TOKEN_TYPE_FIELD = "token_type";
+    private static final String TOKEN_TYPE_VALUE = "Bearer";
+    private static final String SCOPE_FIELD = "scope";
+    private static final String READ_SCOPE = "read";
+    private static final String WRITE_SCOPE = "write";
+    private static final String EXPIRES_IN_FIELD = "expires_in";
+    private static final long EXPIRES_IN_VALUE = 1440;
+
+    @Before
+    public void setup() throws IOException {
+        // Mocking dependencies
+        when(mockHttpClient.execute(any(HttpPost.class))).thenReturn(mockResponse);
+        when(mockResponse.getStatusLine()).thenReturn(mockStatusLine);
+        when(mockStatusLine.getStatusCode()).thenReturn(HttpStatus.SC_OK);
+
+        // Mock APIUtil.getHttpClient() static call
+        mockStatic(APIUtil.class);
+        when(APIUtil.getHttpClient(anyInt(), anyString())).thenReturn(mockHttpClient);
+    }
+
+    /**
+     * Test generated token response when token endpoint is invoked with client credentials grant type
+     */
+    @Test
+    public void testGenerateTokenWithClientCredentialsGrant() throws IOException, APIManagementException, ParseException {
+
+        Map<String, Object> tokenData = new HashMap<>();
+        tokenData.put(ACCESS_TOKEN_FIELD, ACCESS_TOKEN_VALUE);
+        tokenData.put(TOKEN_TYPE_FIELD, TOKEN_TYPE_VALUE);
+        tokenData.put(SCOPE_FIELD, READ_SCOPE);
+        tokenData.put(EXPIRES_IN_FIELD, EXPIRES_IN_VALUE);
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        String jsonResponse = objectMapper.writeValueAsString(tokenData);
+
+        when(mockResponse.getEntity()).thenReturn(new StringEntity(jsonResponse));
+
+        // Call method under test
+        TokenResponse tokenResponse = OAuthClient.generateToken(
+                TOKEN_URL, CLIENT_ID, CLIENT_SECRET, null, null, "CLIENT_CREDENTIALS", null, null);
+
+        // Validate results
+        validateResults(tokenResponse);
+        assertNull(tokenResponse.getRefreshToken());
+        assertEquals(Stream.of(READ_SCOPE).collect(Collectors.toSet()), tokenResponse.getScope());
+    }
+
+    /**
+     * Test generated token response when token endpoint is invoked with password grant type
+     */
+    @Test
+    public void testGenerateTokenWithPasswordGrant() throws Exception {
+
+        Map<String, Object> tokenData = new HashMap<>();
+        tokenData.put(ACCESS_TOKEN_FIELD, ACCESS_TOKEN_VALUE);
+        tokenData.put(REFRESH_TOKEN_FIELD, REFRESH_TOKEN_VALUE);
+        tokenData.put(TOKEN_TYPE_FIELD, TOKEN_TYPE_VALUE);
+        tokenData.put(SCOPE_FIELD, READ_SCOPE + " " + WRITE_SCOPE);
+        tokenData.put(EXPIRES_IN_FIELD, EXPIRES_IN_VALUE);
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        String jsonResponse = objectMapper.writeValueAsString(tokenData);
+        when(mockResponse.getEntity()).thenReturn(new StringEntity(jsonResponse));
+
+        // Call method under test
+        TokenResponse tokenResponse = OAuthClient.generateToken(
+                TOKEN_URL, CLIENT_ID, CLIENT_SECRET, USERNAME, PASSWORD, GRANT_TYPE, null, null);
+
+        // Validate results
+        validateResults(tokenResponse);
+        assertEquals(REFRESH_TOKEN_VALUE, tokenResponse.getRefreshToken());
+        assertEquals(Stream.of(READ_SCOPE + " " + WRITE_SCOPE).collect(Collectors.toSet()), tokenResponse.getScope());
+    }
+
+    /**
+     * Test generated token response when token endpoint is invoked with password grant type and when scope field
+     * is not present in the endpoint response
+     */
+    @Test
+    public void testTokenResponseWithNoScopeField() throws Exception {
+
+        Map<String, Object> tokenData = new HashMap<>();
+        tokenData.put(ACCESS_TOKEN_FIELD, ACCESS_TOKEN_VALUE);
+        tokenData.put(REFRESH_TOKEN_FIELD, REFRESH_TOKEN_VALUE);
+        tokenData.put(TOKEN_TYPE_FIELD, TOKEN_TYPE_VALUE);
+        tokenData.put(EXPIRES_IN_FIELD, EXPIRES_IN_VALUE);
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        String jsonResponse = objectMapper.writeValueAsString(tokenData);
+        when(mockResponse.getEntity()).thenReturn(new StringEntity(jsonResponse));
+
+        // Call method under test
+        TokenResponse tokenResponse = OAuthClient.generateToken(
+                TOKEN_URL, CLIENT_ID, CLIENT_SECRET, USERNAME, PASSWORD, GRANT_TYPE, null, null);
+
+        // Validate results
+        validateResults(tokenResponse);
+        assertEquals(REFRESH_TOKEN_VALUE, tokenResponse.getRefreshToken());
+        assertNull(tokenResponse.getScope());
+    }
+
+    /**
+     * Test generated token response when token endpoint is invoked with password grant type and when the value of the
+     * scope field present in the endpoint response is null
+     */
+    @Test
+    public void testTokenResponseWithScopeValueNull() throws Exception {
+
+        Map<String, Object> tokenData = new HashMap<>();
+        tokenData.put(ACCESS_TOKEN_FIELD, ACCESS_TOKEN_VALUE);
+        tokenData.put(REFRESH_TOKEN_FIELD, REFRESH_TOKEN_VALUE);
+        tokenData.put(TOKEN_TYPE_FIELD, TOKEN_TYPE_VALUE);
+        tokenData.put(SCOPE_FIELD, null);
+        tokenData.put(EXPIRES_IN_FIELD, EXPIRES_IN_VALUE);
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        String jsonResponse = objectMapper.writeValueAsString(tokenData);
+        when(mockResponse.getEntity()).thenReturn(new StringEntity(jsonResponse));
+
+        // Call method under test
+        TokenResponse tokenResponse = OAuthClient.generateToken(
+                TOKEN_URL, CLIENT_ID, CLIENT_SECRET, USERNAME, PASSWORD, GRANT_TYPE, null, null);
+
+        // Validate results
+        validateResults(tokenResponse);
+        assertEquals(REFRESH_TOKEN_VALUE, tokenResponse.getRefreshToken());
+        assertNull(tokenResponse.getScope());
+    }
+
+    /**
+     * Method to validate the generated token response object
+     *
+     * @param tokenResponse TokenResponse object returned by the token endpoint
+     */
+    private void validateResults(TokenResponse tokenResponse) {
+
+        assertNotNull(tokenResponse);
+        assertEquals(ACCESS_TOKEN_VALUE, tokenResponse.getAccessToken());
+        assertEquals(TOKEN_TYPE_VALUE, tokenResponse.getTokenType());
+        assertEquals(String.valueOf(EXPIRES_IN_VALUE), tokenResponse.getExpiresIn());
+        assertNotNull(tokenResponse.getValidTill());
+    }
+}