add more checks in VersionDataLoader.LoadServers, add more tests

tw/twdataloader/version_data_loader.go

@@ -59,11 +59,21 @@ func (dl *VersionDataLoader) LoadServers() ([]*Server, error) {
 		}
 		return nil, fmtedErr
 	}
+	bodyMap, ok := body.(map[interface{}]interface{})
+	if !ok {
+		return nil, errors.Errorf("expected map, got %T", body)
+	}
 
 	var servers []*Server
-	for serverKey, url := range body.(map[interface{}]interface{}) {
-		serverKeyStr := serverKey.(string)
-		urlStr := url.(string)
+	for serverKey, url := range bodyMap {
+		serverKeyStr, ok := serverKey.(string)
+		if !ok {
+			return nil, errors.Errorf("expected string as the key of the map, got %T", serverKey)
+		}
+		urlStr, ok := url.(string)
+		if !ok {
+			return nil, errors.Errorf("expected string as the value of the map, got %T", url)
+		}
 		if serverKeyStr != "" && urlStr != "" {
 			servers = append(servers, &Server{
 				Key: serverKeyStr,

tw/twdataloader/version_data_loader_test.go

@@ -26,19 +26,49 @@ func prepareTestServer(resp string) *httptest.Server {
 }
 
 func TestLoadServers(t *testing.T) {
-	t.Run("invalid payload", func(t *testing.T) {
-		resp := `:"https://pl165.plemiona.pl";s:5:"pl166";s:25:"https://pl166.plemiona.pl";s:5:"pl167";s:25:"https://pl167.plemiona.pl";}`
-		ts := prepareTestServer(resp)
-		defer ts.Close()
+	t.Run("invalid response", func(t *testing.T) {
+		type scenario struct {
+			resp           string
+			expectedErrMsg string
+		}
 
-		dl := NewVersionDataLoader(&VersionDataLoaderConfig{
-			Host:   strings.ReplaceAll(ts.URL, "https://", ""),
-			Client: ts.Client(),
-		})
+		scenarios := []scenario{
+			{
+				resp:           `:"https://pl165.plemiona.pl";s:5:"pl166";s:25:"https://pl166.plemiona.pl";s:5:"pl167";s:25:"https://pl167.plemiona.pl";}`,
+				expectedErrMsg: "couldn't decode the response body into a go value",
+			},
+			{
+				resp:           `a:19:{s:5:"pl150"s:25"https://pl150.plemiona.pl";}`,
+				expectedErrMsg: "expected string as the value of the map, got <nil>",
+			},
+			{
+				resp:           "a:3:{i:0;i:1;i:1;i:2;i:2;i:3;}",
+				expectedErrMsg: "expected string as the key of the map, got int64",
+			},
+			{
+				resp:           `O:8:"stdClass":0:{}`,
+				expectedErrMsg: "expected map, got *phpserialize.PhpObject",
+			},
+			{
+				resp:           `a:2:{s:3:"asd";i:123;s:4:"asd2";i:123;}`,
+				expectedErrMsg: "expected string as the value of the map, got int64",
+			},
+		}
 
-		_, err := dl.LoadServers()
-		assert.NotNil(t, err)
-		assert.Contains(t, err.Error(), "couldn't decode the response body into a go value")
+		for _, scenario := range scenarios {
+			ts := prepareTestServer(scenario.resp)
+
+			dl := NewVersionDataLoader(&VersionDataLoaderConfig{
+				Host:   strings.ReplaceAll(ts.URL, "https://", ""),
+				Client: ts.Client(),
+			})
+
+			_, err := dl.LoadServers()
+			assert.NotNil(t, err)
+			assert.Contains(t, err.Error(), scenario.expectedErrMsg)
+
+			ts.Close()
+		}
 	})
 
 	t.Run("success", func(t *testing.T) {