add support for env variables to the DSL

lang/debug_env_test.go

@@ -0,0 +1,98 @@
+package lang
+
+import (
+	"testing"
+)
+
+func TestSimpleEnvVar(t *testing.T) {
+	// Test the simplest possible environment variable syntax
+	input := `
+server MyApp {
+    host env "HOST"
+}
+`
+
+	ast, err := ParseInput(input)
+	if err != nil {
+		t.Fatalf("Parse error: %v", err)
+	}
+
+	server := ast.Definitions[0].Server
+	if server.Settings[0].Host.EnvVar == nil {
+		t.Fatalf("Expected environment variable")
+	}
+	if server.Settings[0].Host.EnvVar.Name != "HOST" {
+		t.Errorf("Expected HOST, got %s", server.Settings[0].Host.EnvVar.Name)
+	}
+}
+
+func TestLiteralValue(t *testing.T) {
+	// Test that literal values still work
+	input := `
+server MyApp {
+    host "localhost"
+}
+`
+
+	ast, err := ParseInput(input)
+	if err != nil {
+		t.Fatalf("Parse error: %v", err)
+	}
+
+	server := ast.Definitions[0].Server
+	if server.Settings[0].Host.Literal == nil {
+		t.Fatalf("Expected literal value")
+	}
+	if *server.Settings[0].Host.Literal != "localhost" {
+		t.Errorf("Expected localhost, got %s", *server.Settings[0].Host.Literal)
+	}
+}
+
+func TestEnvVarWithDefault(t *testing.T) {
+	// Test environment variable with default value
+	input := `
+server MyApp {
+    host env "HOST" default "localhost"
+}
+`
+
+	ast, err := ParseInput(input)
+	if err != nil {
+		t.Fatalf("Parse error: %v", err)
+	}
+
+	server := ast.Definitions[0].Server
+	envVar := server.Settings[0].Host.EnvVar
+	if envVar == nil {
+		t.Fatalf("Expected environment variable")
+	}
+	if envVar.Name != "HOST" {
+		t.Errorf("Expected HOST, got %s", envVar.Name)
+	}
+	if envVar.Default == nil || *envVar.Default != "localhost" {
+		t.Errorf("Expected default localhost")
+	}
+}
+
+func TestEnvVarRequired(t *testing.T) {
+	// Test environment variable with required flag
+	input := `
+server MyApp {
+    api_key env "API_KEY" required
+}
+`
+
+	ast, err := ParseInput(input)
+	if err != nil {
+		t.Fatalf("Parse error: %v", err)
+	}
+
+	server := ast.Definitions[0].Server
+	envVar := server.Settings[0].APIKey.EnvVar
+	if envVar == nil {
+		t.Fatalf("Expected environment variable")
+	}
+	if !envVar.Required {
+		t.Errorf("Expected required to be true")
+	}
+}