Add tests

Signed-off-by: Matej Vasek <mvasek@redhat.com>

pkg/api/handlers/utils/handler_test.go

@@ -138,3 +138,51 @@ func TestEqualVersion(t *testing.T) {
 			rr.Body.String(), expected)
 	}
 }
+
+func TestErrorEncoderFuncOmit(t *testing.T) {
+	data, err := json.Marshal(struct {
+		Err  error   `json:"err,omitempty"`
+		Errs []error `json:"errs,omitempty"`
+	}{})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dataAsMap := make(map[string]interface{})
+	err = json.Unmarshal(data, &dataAsMap)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, ok := dataAsMap["err"]
+	if ok {
+		t.Errorf("the `err` field should have been omitted")
+	}
+	_, ok = dataAsMap["errs"]
+	if ok {
+		t.Errorf("the `errs` field should have been omitted")
+	}
+
+	dataAsMap = make(map[string]interface{})
+	data, err = json.Marshal(struct {
+		Err  error   `json:"err"`
+		Errs []error `json:"errs"`
+	}{})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = json.Unmarshal(data, &dataAsMap)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, ok = dataAsMap["err"]
+	if !ok {
+		t.Errorf("the `err` field shouldn't have been omitted")
+	}
+	_, ok = dataAsMap["errs"]
+	if !ok {
+		t.Errorf("the `errs` field shouldn't have been omitted")
+	}
+}