From ed988408b9b6990aa37b26a4757d07634d82b551 Mon Sep 17 00:00:00 2001
From: petruki <31597636+petruki@users.noreply.github.com>
Date: Mon, 18 May 2026 13:38:57 -0700
Subject: [PATCH] feat: added isOn must-variant or default

---
 README.md        | 23 ++++++++++++++++++
 switcher.go      | 26 +++++++++++++++++++++
 switcher_test.go | 61 +++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 104 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 964f0ed..78ecb39 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,7 @@ A Go SDK for Switcher API
 - [Usage Examples](#usage-examples)
 	- [Basic Feature Flag Checking](#basic-feature-flag-checking)
 	- [Detailed Response Information](#detailed-response-information)
+	- [Must-variant with default](#must-variant-with-default-response)
 	- [Strategy-Based Feature Flags](#strategy-based-feature-flags)
 	- [Error Handling](#error-handling)
 - [Advanced Features](#advanced-features)
@@ -268,6 +269,28 @@ fmt.Printf("Reason: %s\n", response.Reason)
 fmt.Printf("Metadata: %#v\n", response.Metadata)
 ```
 
+### Must-variant with default response:
+
+Simpified response handling with default values when errors occur:
+
+```go
+feature := client.GetSwitcher("FEATURE_LOGIN_V2")
+
+enabled = feature.IsOnOrDefault(false)
+response := feature.IsOnWithDetailsOrDefault(ResultDetail{
+	Result: false,
+	Reason: "default",
+})
+```
+
+Use the async error channel for non-blocking error handling:
+
+```go
+client.SubscribeNotifyError(func(err error) {
+	fmt.Printf("Switcher Error: %v\n", err)
+})
+```
+
 ### Strategy-Based Feature Flags
 
 #### Method 1: Prepare and Execute
diff --git a/switcher.go b/switcher.go
index 0d30736..3d46869 100644
--- a/switcher.go
+++ b/switcher.go
@@ -149,6 +149,32 @@ func (s *Switcher) IsOnWithDetails() (ResultDetail, error) {
 	return s.submit(true)
 }
 
+// IsOnOrDefault evaluates the Switcher and returns the provided default boolean when an
+// error occurs. The client's error callback is notified when available.
+func (s *Switcher) IsOnOrDefault(def bool) bool {
+	got, err := s.IsOn()
+	if err != nil {
+		if s != nil && s.client != nil {
+			s.client.notifyError(err)
+		}
+		return def
+	}
+	return got
+}
+
+// IsOnWithDetailsOrDefault evaluates the Switcher and returns the provided default ResultDetail
+// when an error occurs. The client's error callback is notified when available.
+func (s *Switcher) IsOnWithDetailsOrDefault(def ResultDetail) ResultDetail {
+	res, err := s.IsOnWithDetails()
+	if err != nil {
+		if s != nil && s.client != nil {
+			s.client.notifyError(err)
+		}
+		return def
+	}
+	return res
+}
+
 func (s *Switcher) submit(showDetails bool) (ResultDetail, error) {
 	execution := s.snapshotForExecution()
 	if cached, ok := s.tryCachedResult(execution, showDetails); ok {
diff --git a/switcher_test.go b/switcher_test.go
index fda3b4e..5b11637 100644
--- a/switcher_test.go
+++ b/switcher_test.go
@@ -3,6 +3,7 @@ package client
 import (
 	"net/http"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -40,6 +41,20 @@ func TestSwitcherValidate(t *testing.T) {
 		err := client.GetSwitcher("FEATURE_LOGIN_V2").Validate()
 		assert.NoError(t, err)
 	})
+
+	t.Run("should return a validation error when the switcher is invalid", func(t *testing.T) {
+		client := NewClient(Context{
+			Domain: "My Domain",
+		})
+
+		got, err := client.GetSwitcher("").IsOn()
+		assert.Equal(t, false, got)
+		assert.EqualError(t, err, "something went wrong: missing or empty required fields (url, component, api_key)")
+
+		gotD, errD := client.GetSwitcher("").IsOnWithDetails()
+		assert.Equal(t, ResultDetail{}, gotD)
+		assert.EqualError(t, errD, "something went wrong: missing or empty required fields (url, component, api_key)")
+	})
 }
 
 func TestSwitcherPrepare(t *testing.T) {
@@ -76,15 +91,49 @@ func TestSwitcherPrepare(t *testing.T) {
 	})
 }
 
-func TestSwitcherIsOnWithDetails(t *testing.T) {
-	t.Run("should return a validation error when the switcher is invalid", func(t *testing.T) {
+func TestSwitcherMustOrDefault(t *testing.T) {
+	t.Run("should return the default value when the switcher is invalid", func(t *testing.T) {
+		client := NewClient(Context{Domain: "My Domain"})
+		var errs []error
+		client.SubscribeNotifyError(func(err error) {
+			errs = append(errs, err)
+		})
+
+		defBool := true
+		got := client.GetSwitcher("").IsOnOrDefault(defBool)
+		assert.Equal(t, defBool, got)
+		if assert.Len(t, errs, 1) {
+			assert.EqualError(t, errs[0], "something went wrong: missing or empty required fields (url, component, api_key)")
+		}
+
+		defs := ResultDetail{Result: true, Reason: "default"}
+		gotD := client.GetSwitcher("").IsOnWithDetailsOrDefault(defs)
+		assert.Equal(t, defs, gotD)
+		if assert.Len(t, errs, 2) {
+			assert.EqualError(t, errs[1], "something went wrong: missing or empty required fields (url, component, api_key)")
+		}
+	})
+
+	t.Run("should return without error when the switcher is valid", func(t *testing.T) {
+		server := newRemoteTestServer(t, remoteTestHandlers{
+			authStatus:     http.StatusOK,
+			authBody:       map[string]any{"token": "[token]", "exp": time.Now().Add(time.Hour).Unix()},
+			criteriaStatus: http.StatusOK,
+			criteriaBody:   map[string]any{"result": true, "reason": "Success", "metadata": map[string]any{"env": "prod"}},
+		})
+		defer server.Close()
+
 		client := NewClient(Context{
-			Domain: "My Domain",
+			Domain:    "My Domain",
+			URL:       server.URL,
+			APIKey:    "[YOUR_API_KEY]",
+			Component: "MyApp",
 		})
 
-		got, err := client.GetSwitcher("").IsOnWithDetails()
+		got := client.GetSwitcher("MY_SWITCHER").IsOnOrDefault(false)
+		assert.Equal(t, true, got)
 
-		assert.Equal(t, ResultDetail{}, got)
-		assert.EqualError(t, err, "something went wrong: missing or empty required fields (url, component, api_key)")
+		gotD := client.GetSwitcher("MY_SWITCHER").IsOnWithDetailsOrDefault(ResultDetail{Result: false, Reason: "default"})
+		assert.Equal(t, ResultDetail{Result: true, Reason: "Success", Metadata: map[string]any{"env": "prod"}}, gotD)
 	})
 }