Use fallback value if client is not initialized

If no defaultClient is initialized, we should return the provided
fallback value instead of `false`.

client.go

@@ -267,17 +267,8 @@ func (uc *Client) isEnabled(feature string, options ...FeatureOption) api.Strate
 	}
 
 	if f == nil {
-		if opts.fallbackFunc != nil {
-			return api.StrategyResult{
-				Enabled: opts.fallbackFunc(feature, ctx),
-			}
-		} else if opts.fallback != nil {
-			return api.StrategyResult{
-				Enabled: *opts.fallback,
-			}
-		}
 		return api.StrategyResult{
-			Enabled: false,
+			Enabled: opts.FallbackForFeature(feature, ctx),
 		}
 	}
 

config.go

@@ -159,6 +159,16 @@ type featureOption struct {
 	resolver     FeatureResolver
 }
 
+func (fo featureOption) FallbackForFeature(feature string, ctx *context.Context) bool {
+	if fo.fallbackFunc != nil {
+		return fo.fallbackFunc(feature, ctx)
+	}
+	if fo.fallback != nil {
+		return *fo.fallback
+	}
+	return false
+}
+
 // FeatureOption provides options for querying if a feature is enabled or not.
 type FeatureOption func(*featureOption)
 

unleash.go

@@ -38,7 +38,11 @@ type RepositoryListener interface {
 // IsEnabled queries the default client whether or not the specified feature is enabled or not.
 func IsEnabled(feature string, options ...FeatureOption) bool {
 	if defaultClient == nil {
-		return false
+		var opts featureOption
+		for _, o := range options {
+			o(&opts)
+		}
+		return opts.FallbackForFeature(feature, opts.ctx)
 	}
 	return defaultClient.IsEnabled(feature, options...)
 }

unleash_test.go

@@ -64,3 +64,10 @@ func Test_withVariantsAndANonExistingStrategyName(t *testing.T) {
 		t.Fatalf("Expected feature to be disabled because Environment does not exist as strategy")
 	}
 }
+
+func Test_IsEnabledWithUninitializedClient(t *testing.T) {
+	result := unleash.IsEnabled("foo", unleash.WithFallback(true))
+	if !result {
+		t.Fatalf("Expected true")
+	}
+}