Add simple end to end test

cmd/fyne/internal/commands/translate_test.go

@@ -0,0 +1,59 @@
+package commands
+
+import (
+	"encoding/json"
+	"os"
+	"path"
+	"testing"
+)
+
+const exampleSource = `
+package main
+
+func main() {
+	lang.X("example", "Example")
+}
+`
+
+func TestTranslate(t *testing.T) {
+	dir := t.TempDir()
+	src := path.Join(dir, "foo.go")
+
+	if err := os.Chdir(dir); err != nil {
+		t.Fatal(err)
+	}
+
+	f, err := os.Create(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Write([]byte(exampleSource))
+	f.Close()
+
+	opts := translateOpts{}
+	dst := "en.json"
+
+	if err := updateTranslationsFile(&opts, dst, []string{src}); err != nil {
+		t.Fatal(err)
+	}
+
+	f, err = os.Open(dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	translations := make(map[string]interface{})
+	dec := json.NewDecoder(f)
+	if err := dec.Decode(&translations); err != nil {
+		t.Fatal(err)
+	}
+
+	key := "example"
+	val, found := translations[key]
+	if !found {
+		t.Errorf("failed to find key: %v", key)
+	}
+	if val != "Example" {
+		t.Errorf("invalid value for key: %v: %v", key, val)
+	}
+}