lua: validate script extension after resolving symlinks

common/lua/program_test.go

@@ -21,10 +21,7 @@ import (
 )
 
 func TestProgramStatesAreIndependent(t *testing.T) {
-	path := filepath.Join(t.TempDir(), "state.lua")
-	if err := os.WriteFile(path, []byte("value = (value or 0) + 1"), 0o600); err != nil {
-		t.Fatal(err)
-	}
+	path := writeTestScript(t, "value = (value or 0) + 1")
 	program, err := Compile(path)
 	if err != nil {
 		t.Fatal(err)
@@ -191,6 +188,22 @@ func TestCompileInlineDiagnostics(t *testing.T) {
 }
 */
 
+func TestCompileFileExtension(t *testing.T) {
+	for _, name := range []string{"script", "script.dat", "script.lua.txt", "script.LUA"} {
+		path := filepath.Join(t.TempDir(), name)
+		if err := os.WriteFile(path, []byte("value = 42"), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		if program, err := Compile(path); program != nil || err == nil || !strings.Contains(err.Error(), "Lua file extension must be .lua") {
+			t.Fatalf("Compile(%q) = %v, %v; want nil program and .lua extension error", path, program, err)
+		}
+	}
+	path := writeTestScript(t, "value = 42") + string(filepath.Separator) + "."
+	if program, err := Compile(path); program == nil || err != nil {
+		t.Fatalf("Compile(%q) = %v, %v; want acceptance of the resolved .lua path", path, program, err)
+	}
+}
+
 func TestCompileRejectsReadFailure(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "unreadable.lua")
 	if err := os.WriteFile(path, []byte("value = 42"), 0o600); err != nil {
@@ -255,6 +268,10 @@ func writeTestScript(t *testing.T, code string) string {
 	if err := os.WriteFile(path, []byte(code), 0o600); err != nil {
 		t.Fatal(err)
 	}
+	path, err := filepath.EvalSymlinks(path)
+	if err != nil {
+		t.Fatal(err)
+	}
 	return path
 }