Added OAuthException and Tests, fixes #287

src/main/kotlin/com/workos/WorkOS.kt

@@ -7,11 +7,13 @@ import com.github.kittinunf.fuel.core.Request
 import com.github.kittinunf.fuel.core.Response
 import com.workos.auditlogs.AuditLogsApi
 import com.workos.common.exceptions.BadRequestException
+import com.workos.common.exceptions.OAuthException
 import com.workos.common.exceptions.GenericServerException
 import com.workos.common.exceptions.NotFoundException
 import com.workos.common.exceptions.UnauthorizedException
 import com.workos.common.exceptions.UnprocessableEntityException
 import com.workos.common.http.BadRequestExceptionResponse
+import com.workos.common.http.OAuthErrorResponse
 import com.workos.common.http.GenericErrorResponse
 import com.workos.common.http.RequestConfig
 import com.workos.common.http.UnprocessableEntityExceptionResponse
@@ -363,8 +365,15 @@ class WorkOS(
 
     when (val status = response.statusCode) {
       400 -> {
-        val responseData = mapper.readValue(payload, BadRequestExceptionResponse::class.java)
-        throw BadRequestException(responseData.message, responseData.code, responseData.errors, requestId)
+        // Try to parse as OAuth error first
+        val isOAuthError = payload.contains("\"error\"") && payload.contains("\"error_description\"")
+        if (isOAuthError) {
+          val oauthError = mapper.readValue(payload, OAuthErrorResponse::class.java)
+          throw OAuthException(oauthError.error, oauthError.error_description, requestId)
+        } else {
+          val responseData = mapper.readValue(payload, BadRequestExceptionResponse::class.java)
+          throw BadRequestException(responseData.message, responseData.code, responseData.errors, requestId)
+        }
       }
 
       401 -> {

src/main/kotlin/com/workos/common/exceptions/OAuthException.kt

@@ -0,0 +1,14 @@
+package com.workos.common.exceptions
+
+/**
+ * Thrown when the API returns an OAuth error (e.g., invalid_grant).
+ *
+ * @param error The OAuth error code.
+ * @param errorDescription The OAuth error description.
+ * @param requestId The ID of the correlating request specified in the 'X-Request-ID' header.
+ */
+class OAuthException(
+  val error: String?,
+  val errorDescription: String?,
+  val requestId: String
+) : Exception(errorDescription)

src/main/kotlin/com/workos/common/http/OAuthErrorResponse.kt

@@ -0,0 +1,6 @@
+package com.workos.common.http
+
+data class OAuthErrorResponse(
+    val error: String?,
+    val error_description: String?
+)

src/test/kotlin/com/workos/test/user_management/OAuthErrorHandlingTest.kt

@@ -0,0 +1,39 @@
+
+package com.workos.test.user_management
+
+
+import com.workos.common.exceptions.OAuthException
+import com.workos.test.TestBase
+import org.junit.jupiter.api.Assertions.assertThrows
+import kotlin.test.Test
+
+class OAuthErrorHandlingTest : TestBase() {
+    val workos = createWorkOSClient()
+
+    @Test
+    fun authenticateWithCodeShouldThrowOAuthExceptionOnInvalidGrant() {
+                        stubResponse(
+                                "/user_management/authenticate",
+                                """
+                                {
+                                    "error" : "invalid_grant",
+                                    "error_description" : "The code 'D01K0EWQ9V6SYP9F5D14QPHBQ8Edd' has expired or is invalid."
+                                }
+                                """,
+                                responseStatus = 400,
+                                requestBody = """{
+                                    "client_id": "client_id",
+                                    "client_secret": "apiKey",
+                                    "grant_type": "authorization_code",
+                                    "code": "invalid_code"
+                                }"""
+                        )
+
+        assertThrows(OAuthException::class.java) {
+            workos.userManagement.authenticateWithCode(
+                "client_id",
+                "invalid_code"
+            )
+        }
+    }
+}