Show better error messages when requests fail

src/main/java/io/ipinfo/api/errors/ErrorResponseException.java

@@ -1,9 +1,29 @@
 package io.ipinfo.api.errors;
 
 public class ErrorResponseException extends RuntimeException {
-    public ErrorResponseException() {}
+
+    private final int statusCode;
+
+    public ErrorResponseException() {
+        this.statusCode = -1;
+    }
 
     public ErrorResponseException(Exception ex) {
         super(ex);
+        this.statusCode = -1;
+    }
+
+    public ErrorResponseException(int statusCode, String responseBody) {
+        super(
+            "Unexpected API response (status " +
+                statusCode +
+                "): " +
+                responseBody
+        );
+        this.statusCode = statusCode;
+    }
+
+    public int getStatusCode() {
+        return statusCode;
     }
 }

src/main/java/io/ipinfo/api/request/BaseRequest.java

@@ -9,7 +9,8 @@
 import okhttp3.Response;
 
 public abstract class BaseRequest<T> {
-    protected final static Gson gson = new Gson();
+
+    protected static final Gson gson = new Gson();
     private final OkHttpClient client;
     private final String token;
 
@@ -20,11 +21,12 @@ protected BaseRequest(OkHttpClient client, String token) {
 
     public abstract T handle() throws RateLimitedException;
 
-    public Response handleRequest(Request.Builder request) throws RateLimitedException {
+    public Response handleRequest(Request.Builder request)
+        throws RateLimitedException {
         request
-                .addHeader("Authorization", Credentials.basic(token, ""))
-                .addHeader("user-agent", "IPinfoClient/Java/3.3.0")
-                .addHeader("Content-Type", "application/json");
+            .addHeader("Authorization", Credentials.basic(token, ""))
+            .addHeader("user-agent", "IPinfoClient/Java/3.3.0")
+            .addHeader("Content-Type", "application/json");
 
         Response response;
 
@@ -43,7 +45,16 @@ public Response handleRequest(Request.Builder request) throws RateLimitedExcepti
             throw new RateLimitedException();
         }
 
+        if (!response.isSuccessful()) {
+            String body = "";
+            try {
+                if (response.body() != null) {
+                    body = response.body().string();
+                }
+            } catch (Exception ignored) {}
+            throw new ErrorResponseException(response.code(), body);
+        }
+
         return response;
     }
 }
-

src/test/java/io/ipinfo/IPinfoTest.java

@@ -1,6 +1,7 @@
 package io.ipinfo;
 
 import io.ipinfo.api.IPinfo;
+import io.ipinfo.api.errors.ErrorResponseException;
 import io.ipinfo.api.errors.RateLimitedException;
 import io.ipinfo.api.model.ASNResponse;
 import io.ipinfo.api.model.IPResponse;
@@ -388,4 +389,47 @@ public void testLookupResproxyEmpty() throws IOException {
             server.shutdown();
         }
     }
+
+    @Test
+    public void testServerErrorThrowsErrorResponseException() throws IOException {
+        MockWebServer server = new MockWebServer();
+        server.enqueue(new MockResponse()
+            .setResponseCode(503)
+            .setBody("Service Temporarily Unavailable")
+            .addHeader("Content-Type", "text/plain"));
+        server.start();
+
+        OkHttpClient client = new OkHttpClient.Builder()
+            .addInterceptor(chain -> {
+                okhttp3.Request originalRequest = chain.request();
+                okhttp3.HttpUrl newUrl = originalRequest.url().newBuilder()
+                    .scheme("http")
+                    .host(server.getHostName())
+                    .port(server.getPort())
+                    .build();
+                okhttp3.Request newRequest = originalRequest.newBuilder()
+                    .url(newUrl)
+                    .build();
+                return chain.proceed(newRequest);
+            })
+            .build();
+
+        IPinfo ii = new IPinfo.Builder()
+            .setToken("test_token")
+            .setClient(client)
+            .build();
+
+        try {
+            ErrorResponseException ex = assertThrows(
+                ErrorResponseException.class,
+                () -> ii.lookupIP("8.8.8.8")
+            );
+            assertEquals(503, ex.getStatusCode());
+            assertTrue(ex.getMessage().contains("503"), "message should contain status code");
+            assertTrue(ex.getMessage().contains("Service Temporarily Unavailable"),
+                "message should contain response body");
+        } finally {
+            server.shutdown();
+        }
+    }
 }