diff --git a/compiler/internal/env/env_test.go b/compiler/internal/env/env_test.go
new file mode 100644
index 00000000..14a49808
--- /dev/null
+++ b/compiler/internal/env/env_test.go
@@ -0,0 +1,161 @@
+package env
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestGOROOT(t *testing.T) {
+	// Test with GOROOT environment variable set
+	t.Run("with GOROOT env", func(t *testing.T) {
+		origGoRoot := os.Getenv("GOROOT")
+		defer os.Setenv("GOROOT", origGoRoot)
+
+		expected := "/custom/goroot"
+		os.Setenv("GOROOT", expected)
+		if got := GOROOT(); got != expected {
+			t.Errorf("GOROOT() = %v, want %v", got, expected)
+		}
+	})
+
+	// Test without GOROOT environment variable
+	t.Run("without GOROOT env", func(t *testing.T) {
+		origGoRoot := os.Getenv("GOROOT")
+		defer os.Setenv("GOROOT", origGoRoot)
+
+		os.Setenv("GOROOT", "")
+		if got := GOROOT(); got == "" {
+			t.Error("GOROOT() should not return empty when using go env")
+		}
+	})
+}
+
+func TestLLGoRuntimeDir(t *testing.T) {
+	// Test with valid LLGO_ROOT
+	t.Run("with valid LLGO_ROOT", func(t *testing.T) {
+		origLLGoRoot := os.Getenv("LLGO_ROOT")
+		defer os.Setenv("LLGO_ROOT", origLLGoRoot)
+
+		tmpDir := t.TempDir()
+		runtimeDir := filepath.Join(tmpDir, "runtime")
+		os.MkdirAll(runtimeDir, 0755)
+		goModContent := []byte("module github.com/goplus/llgo/runtime\n")
+		if err := os.WriteFile(filepath.Join(runtimeDir, "go.mod"), goModContent, 0644); err != nil {
+			t.Fatal(err)
+		}
+
+		os.Setenv("LLGO_ROOT", tmpDir)
+		expected := runtimeDir
+		if got := LLGoRuntimeDir(); got != expected {
+			t.Errorf("LLGoRuntimeDir() = %v, want %v", got, expected)
+		}
+	})
+
+	// Test with invalid LLGO_ROOT
+	t.Run("with invalid LLGO_ROOT", func(t *testing.T) {
+		origLLGoRoot := os.Getenv("LLGO_ROOT")
+		defer os.Setenv("LLGO_ROOT", origLLGoRoot)
+
+		os.Setenv("LLGO_ROOT", "/nonexistent/path")
+		if got := LLGoRuntimeDir(); got != "" {
+			t.Errorf("LLGoRuntimeDir() = %v, want empty string", got)
+		}
+	})
+}
+
+func TestLLGoROOT(t *testing.T) {
+	// Test with valid LLGO_ROOT environment variable
+	t.Run("with valid LLGO_ROOT env", func(t *testing.T) {
+		origLLGoRoot := os.Getenv("LLGO_ROOT")
+		defer os.Setenv("LLGO_ROOT", origLLGoRoot)
+
+		tmpDir := t.TempDir()
+		runtimeDir := filepath.Join(tmpDir, "runtime")
+		os.MkdirAll(runtimeDir, 0755)
+		goModContent := []byte("module github.com/goplus/llgo/runtime\n")
+		if err := os.WriteFile(filepath.Join(runtimeDir, "go.mod"), goModContent, 0644); err != nil {
+			t.Fatal(err)
+		}
+
+		os.Setenv("LLGO_ROOT", tmpDir)
+		if got := LLGoROOT(); got != tmpDir {
+			t.Errorf("LLGoROOT() = %v, want %v", got, tmpDir)
+		}
+	})
+
+	// Test with invalid LLGO_ROOT environment variable
+	t.Run("with invalid LLGO_ROOT env", func(t *testing.T) {
+		origLLGoRoot := os.Getenv("LLGO_ROOT")
+		defer os.Setenv("LLGO_ROOT", origLLGoRoot)
+
+		os.Setenv("LLGO_ROOT", "/nonexistent/path")
+		if got := LLGoROOT(); got != "" {
+			t.Errorf("LLGoROOT() = %v, want empty string", got)
+		}
+	})
+
+	// Test with empty LLGO_ROOT environment variable
+	t.Run("with empty LLGO_ROOT env", func(t *testing.T) {
+		origLLGoRoot := os.Getenv("LLGO_ROOT")
+		defer os.Setenv("LLGO_ROOT", origLLGoRoot)
+
+		os.Setenv("LLGO_ROOT", "")
+		// Result depends on executable path, just ensure it doesn't panic
+		LLGoROOT()
+	})
+}
+
+func TestIsLLGoRoot(t *testing.T) {
+	// Test with empty root
+	t.Run("empty root", func(t *testing.T) {
+		if root, ok := isLLGoRoot(""); ok {
+			t.Errorf("isLLGoRoot('') = %v, %v, want '', false", root, ok)
+		}
+	})
+
+	// Test with invalid path
+	t.Run("invalid path", func(t *testing.T) {
+		if root, ok := isLLGoRoot(string([]byte{0})); ok {
+			t.Errorf("isLLGoRoot(invalid) = %v, %v, want '', false", root, ok)
+		}
+	})
+
+	// Test with non-existent path
+	t.Run("non-existent path", func(t *testing.T) {
+		if root, ok := isLLGoRoot("/nonexistent/path"); ok {
+			t.Errorf("isLLGoRoot(nonexistent) = %v, %v, want '', false", root, ok)
+		}
+	})
+
+	// Test with valid path but invalid go.mod
+	t.Run("invalid go.mod", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		runtimeDir := filepath.Join(tmpDir, "runtime")
+		os.MkdirAll(runtimeDir, 0755)
+		goModContent := []byte("module wrong/module/name\n")
+		if err := os.WriteFile(filepath.Join(runtimeDir, "go.mod"), goModContent, 0644); err != nil {
+			t.Fatal(err)
+		}
+
+		if root, ok := isLLGoRoot(tmpDir); ok {
+			t.Errorf("isLLGoRoot(invalid_mod) = %v, %v, want '', false", root, ok)
+		}
+	})
+
+	// Test with valid path and valid go.mod
+	t.Run("valid path and go.mod", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		runtimeDir := filepath.Join(tmpDir, "runtime")
+		os.MkdirAll(runtimeDir, 0755)
+		goModContent := []byte("module github.com/goplus/llgo/runtime\n")
+		if err := os.WriteFile(filepath.Join(runtimeDir, "go.mod"), goModContent, 0644); err != nil {
+			t.Fatal(err)
+		}
+
+		absPath, _ := filepath.Abs(tmpDir)
+		if root, ok := isLLGoRoot(tmpDir); !ok || root != absPath {
+			t.Errorf("isLLGoRoot(valid) = %v, %v, want %v, true", root, ok, absPath)
+		}
+	})
+}