feat: Add pollErrorHandler to handle pollEnvironment errors

Author: ajinkyasurya

client.go

@@ -26,11 +26,12 @@ type Client struct {
 	analyticsProcessor *AnalyticsProcessor
 	defaultFlagHandler func(string) (Flag, error)
 
-	client         *resty.Client
-	ctxLocalEval   context.Context
-	ctxAnalytics   context.Context
-	log            Logger
-	offlineHandler OfflineHandler
+	client           *resty.Client
+	ctxLocalEval     context.Context
+	ctxAnalytics     context.Context
+	log              Logger
+	offlineHandler   OfflineHandler
+	pollErrorHandler func(error)
 }
 
 // NewClient creates instance of Client with given configuration.
@@ -244,6 +245,9 @@ func (c *Client) pollEnvironment(ctx context.Context) {
 		err := c.UpdateEnvironment(ctx)
 		if err != nil {
 			c.log.Errorf("Failed to update environment: %v", err)
+			if c.pollErrorHandler != nil {
+			    c.pollErrorHandler(err)
+			}
 		}
 	}
 	update()

client_export_test.go

@@ -0,0 +1,7 @@
+package flagsmith
+
+import "context"
+
+func PollEnvironment(client *Client, ctx context.Context) {
+    client.pollEnvironment(ctx)
+}

client_test.go

@@ -675,3 +675,35 @@ func TestOfflineHandlerIsUsedWhenRequestFails(t *testing.T) {
 	assert.Equal(t, fixtures.Feature1ID, allFlags[0].FeatureID)
 	assert.Equal(t, fixtures.Feature1Value, allFlags[0].Value)
 }
+
+func TestPollErrorHandlerIsUsedWhenPollFails(t *testing.T) {
+    // Given
+    ctx := context.Background()
+    expectedErrorMessage := "flagsmith: unexpected response from Flagsmith API: 500 Internal Server Error"
+    var capturedError error
+
+	server := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+		rw.WriteHeader(http.StatusInternalServerError)
+	}))
+	defer server.Close()
+
+	// When
+	client := flagsmith.NewClient(fixtures.EnvironmentAPIKey,
+		flagsmith.WithBaseURL(server.URL+"/api/v1/"),
+		flagsmith.WithEnvironmentRefreshInterval(time.Duration(2)*time.Second),
+		flagsmith.WithPollErrorHandler(func(err error) {
+		    capturedError = err
+		}),
+	)
+
+    // when
+    go func() { flagsmith.PollEnvironment(client, ctx) }()
+
+    // stop method in 2 seconds
+    time.Sleep(1 * time.Second)
+    ctx.Done()
+
+    // Then
+    assert.NotNil(t, capturedError)
+    assert.Contains(t, capturedError.Error(), expectedErrorMessage)
+}

options.go

@@ -117,3 +117,10 @@ func WithOfflineMode() Option {
 		c.config.offlineMode = true
 	}
 }
+
+// WithPollErrorHandler provides a way to handle errors that occur during polling of environment
+func WithPollErrorHandler(handler func(err error)) Option {
+    return func(c *Client) {
+        c.pollErrorHandler = handler
+    }
+}