feat(update): make default GOLDEN_UPDATE env var check case-insensitive (#10)

update.go

@@ -1,6 +1,9 @@
 package golden
 
-import "os"
+import (
+	"os"
+	"strings"
+)
 
 var truthyStrings = []string{"1", "y", "t", "yes", "on", "true"}
 
@@ -14,7 +17,7 @@ type UpdateFunc func() bool
 func EnvUpdateFunc() bool {
 	env := os.Getenv("GOLDEN_UPDATE")
 	for _, v := range truthyStrings {
-		if env == v {
+		if strings.EqualFold(env, v) {
 			return true
 		}
 	}

update_test.go

@@ -90,6 +90,32 @@ var envUpdateFuncTestCases = []struct {
 		env:  map[string]string{"GOLDEN_UPDATE": "foobarnopebbq"},
 		want: false,
 	},
+	// Case-insensitive test cases
+	{
+		name: "GOLDEN_UPDATE set to Y (uppercase)",
+		env:  map[string]string{"GOLDEN_UPDATE": "Y"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to TRUE (uppercase)",
+		env:  map[string]string{"GOLDEN_UPDATE": "TRUE"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to Yes (mixed case)",
+		env:  map[string]string{"GOLDEN_UPDATE": "Yes"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to ON (uppercase)",
+		env:  map[string]string{"GOLDEN_UPDATE": "ON"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to TrUe (mixed case)",
+		env:  map[string]string{"GOLDEN_UPDATE": "TrUe"},
+		want: true,
+	},
 }
 
 func TestEnvUpdateFunc(t *testing.T) {