Started working on builtins

ucl/builtins/os_test.go

@@ -0,0 +1,36 @@
+package builtins_test
+
+import (
+	"context"
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"ucl.lmika.dev/ucl"
+	"ucl.lmika.dev/ucl/builtins"
+)
+
+func TestOS_Env(t *testing.T) {
+	tests := []struct {
+		descr string
+		eval  string
+		want  any
+	}{
+		{descr: "env value", eval: `os:env "MY_ENV"`, want: "my env value"},
+		{descr: "missing env value", eval: `os:env "MISSING_THING"`, want: ""},
+		{descr: "default env value (str)", eval: `os:env "MISSING_THING" "my default"`, want: "my default"},
+		{descr: "default env value (int)", eval: `os:env "MISSING_THING" 1352`, want: 1352},
+		{descr: "default env value (nil)", eval: `os:env "MISSING_THING" ()`, want: nil},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.descr, func(t *testing.T) {
+			t.Setenv("MY_ENV", "my env value")
+
+			inst := ucl.New(
+				ucl.WithModule(builtins.OS()),
+			)
+			res, err := inst.Eval(context.Background(), tt.eval)
+			assert.NoError(t, err)
+			assert.Equal(t, tt.want, res)
+		})
+	}
+}