[#370] Added error message parsing for missing user

Fixes #370

Author: hossain-khan

src/main/kotlin/dev/hossain/githubstats/util/ErrorInfo.kt

@@ -24,18 +24,42 @@ data class ErrorThreshold(
 /**
  * Error response from GitHub API.
  *
- * Sample error message.
+ * Sample error messages.
  * ```json
  * {"message":"Bad credentials","documentation_url":"https://docs.github.com/rest"}
  *
  * {"message":"Validation Failed","errors":[{"resource":"Issue","code":"missing_field","field":"title"}],"documentation_url":"https://docs.github.com/rest/reference/issues#create-an-issue"}
  *
  * {"message":"Not Found","documentation_url":"https://docs.github.com/rest/pulls/pulls#get-a-pull-request","status":"404"}
+ *
+ * {"message":"Validation Failed","errors":[{"message":"The listed users cannot be searched either because the users do not exist or you do not have permission to view the users.","resource":"Search","field":"q","code":"invalid"}],"documentation_url":"https://docs.github.com/v3/search/","status":"422"}
  * ```
  */
 @JsonClass(generateAdapter = true)
 data class GithubError(
     @Json(name = "message") val message: String,
     @Json(name = "documentation_url") val documentationUrl: String,
     @Json(name = "status") val status: Int? = null,
+    @Json(name = "errors") val errors: List<GithubErrorDetail> = emptyList(),
+)
+
+/**
+ * Error details from GitHub API.
+ *
+ * Example error detail:
+ * ```json
+ * {
+ *   "resource": "Search",
+ *   "code": "invalid",
+ *   "message": "The listed users cannot be searched either because the users do not exist or you do not have permission to view the users.",
+ *   "field": "q"
+ * }
+ * ```
+ */
+@JsonClass(generateAdapter = true)
+data class GithubErrorDetail(
+    @Json(name = "resource") val resource: String,
+    @Json(name = "code") val code: String,
+    @Json(name = "field") val field: String,
+    @Json(name = "message") val message: String,
 )

src/main/kotlin/dev/hossain/githubstats/util/ErrorProcessor.kt

@@ -21,6 +21,36 @@ class ErrorProcessor {
          * ```
          */
         private const val TOKEN_ERROR_MESSAGE = "Bad credentials"
+
+        /**
+         * Error message when search query is invalid.
+         *
+         * Sample error message.
+         * ```json
+         * {"message":"Validation Failed","errors":[{"message":"The listed users cannot be searched.","resource":"Search","field":"q","code":"invalid"}],"documentation_url":"https://docs.github.com/v3/search/","status":"422"}
+         * ```
+         */
+        private const val VALIDATION_FAILED_ERROR_MESSAGE = "Validation Failed"
+
+        /**
+         * Resource type for search error.
+         */
+        private const val RESOURCE_TYPE_SEARCH = "Search"
+
+        /**
+         * Check if user is missing in the search query.
+         */
+        fun isUserMissingError(githubError: GithubError?): Boolean {
+            if (githubError == null || githubError.message != VALIDATION_FAILED_ERROR_MESSAGE) {
+                return false
+            }
+
+            return githubError.errors.any {
+                it.resource == RESOURCE_TYPE_SEARCH &&
+                    // Yes, hardcoding the server message string to avoid any false positive
+                    it.message.contains("users cannot be searched")
+            }
+        }
     }
 
     /**

src/test/kotlin/dev/hossain/githubstats/util/ErrorProcessorTest.kt

@@ -117,4 +117,72 @@ class ErrorProcessorTest {
         assertThat(errorInfo.errorMessage).contains("HTTP 404")
         assertThat(errorInfo.githubError).isNull()
     }
+
+    @Test
+    fun `getDetailedError - given HttpException with JSON github errors list - returns ErrorInfo processed data with errors`() {
+        // language=JSON
+        val jsonErrorBody =
+            """
+            {
+              "message": "Validation Failed",
+              "errors": [
+                {
+                  "message": "The listed users cannot be searched either because the users do not exist or you do not have permission to view the users.",
+                  "resource": "Search",
+                  "field": "q",
+                  "code": "invalid"
+                }
+              ],
+              "documentation_url": "https://docs.github.com/v3/search/",
+              "status": "422"
+            }
+            """.trimIndent()
+        val httpException = HttpException(Response.error<Any>(422, jsonErrorBody.toResponseBody("application/json".toMediaTypeOrNull())))
+        val errorProcessor = ErrorProcessor()
+
+        val errorInfo = errorProcessor.getDetailedError(httpException)
+
+        assertThat(errorInfo).isInstanceOf(ErrorInfo::class.java)
+        assertThat(errorInfo.githubError?.message).isEqualTo("Validation Failed")
+        assertThat(errorInfo.githubError?.status).isEqualTo(422)
+        assertThat(errorInfo.githubError?.errors).isNotEmpty()
+
+        val githubErrorDetail = errorInfo.githubError?.errors?.get(0)!!
+        assertThat(
+            githubErrorDetail.message,
+        ).isEqualTo(
+            "The listed users cannot be searched either because the users do not exist or you do not have permission to view the users.",
+        )
+        assertThat(githubErrorDetail.resource).isEqualTo("Search")
+        assertThat(githubErrorDetail.field).isEqualTo("q")
+        assertThat(githubErrorDetail.code).isEqualTo("invalid")
+    }
+
+    @Test
+    fun `getDetailedError - given HttpException with JSON github error user not found - validates user not found`() {
+        // language=JSON
+        val jsonErrorBody =
+            """
+            {
+              "message": "Validation Failed",
+              "errors": [
+                {
+                  "message": "The listed users cannot be searched either because the users do not exist or you do not have permission to view the users.",
+                  "resource": "Search",
+                  "field": "q",
+                  "code": "invalid"
+                }
+              ],
+              "documentation_url": "https://docs.github.com/v3/search/",
+              "status": "422"
+            }
+            """.trimIndent()
+        val httpException = HttpException(Response.error<Any>(422, jsonErrorBody.toResponseBody("application/json".toMediaTypeOrNull())))
+        val errorProcessor = ErrorProcessor()
+
+        val errorInfo = errorProcessor.getDetailedError(httpException)
+
+        assertThat(errorInfo).isInstanceOf(ErrorInfo::class.java)
+        assertThat(ErrorProcessor.isUserMissingError(errorInfo.githubError)).isTrue()
+    }
 }