Enhances error handling in resource() (with tests)

pkg/scim/client.go

@@ -377,5 +377,15 @@ func (c Client) resource(resp *http.Response, res Resource) error {
 	if err != nil {
 		return err
 	}
-	return json.Unmarshal(body, res)
+
+	err = json.Unmarshal(body, res)
+	if err != nil {
+		return CodecError{
+			Err:  err.Error(),
+			Op:   Unmarshal,
+			Body: body,
+		}
+	}
+
+	return nil
 }

pkg/scim/client_test.go

@@ -257,6 +257,36 @@ func TestResourceOrError(t *testing.T) {
 				Description: "Bad request",
 			},
 		},
+		{
+			name: "No body",
+			mock: httptest.MockTransport{
+				Req: &http.Request{
+					Header: map[string][]string{},
+				},
+				Resp: &http.Response{
+					StatusCode: 200,
+					Body:       nil,
+				},
+			},
+			exp: errors.New("<No body>"),
+		},
+		{
+			name: "Bad JSON",
+			mock: httptest.MockTransport{
+				Req: &http.Request{
+					Header: map[string][]string{},
+				},
+				Resp: &http.Response{
+					StatusCode: 200,
+					Body:       ioutil.NopCloser(strings.NewReader("}")),
+				},
+			},
+			exp: CodecError{
+				Err:  "invalid character '}' looking for beginning of value",
+				Op:   Unmarshal,
+				Body: []byte("}"),
+			},
+		},
 		{
 			name: "Correct",
 			mock: httptest.MockTransport{

pkg/scim/codec.go

@@ -0,0 +1,20 @@
+package scim
+
+import "fmt"
+
+type CodecOperation string
+
+const (
+	Marshal   CodecOperation = "Marshal"
+	Unmarshal CodecOperation = "Unmarshal"
+)
+
+type CodecError struct {
+	Err  string
+	Op   CodecOperation
+	Body []byte
+}
+
+func (ce CodecError) Error() string {
+	return fmt.Sprintf("Err: %s, Operation: %s, Body: %s", ce.Err, ce.Op, string(ce.Body))
+}