compiler: support named returns

pkg/compiler/return_test.go

@@ -1,8 +1,12 @@
 package compiler_test
 
 import (
+	"fmt"
 	"math/big"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestReturnInt64(t *testing.T) {
@@ -92,3 +96,30 @@ func TestSingleReturn(t *testing.T) {
 	`
 	eval(t, src, big.NewInt(9))
 }
+
+func TestNamedReturn(t *testing.T) {
+	src := `package foo
+	func Main() (a int, b int) {
+		a = 1
+		b = 2
+		c := 3
+		_ = c
+		return %s
+	}`
+
+	runCase := func(ret string, result ...interface{}) func(t *testing.T) {
+		return func(t *testing.T) {
+			src := fmt.Sprintf(src, ret)
+			v := vmAndCompile(t, src)
+			require.NoError(t, v.Run())
+			require.Equal(t, len(result), v.Estack().Len())
+			for i := range result {
+				assert.EqualValues(t, result[i], v.Estack().Pop().Value())
+			}
+		}
+	}
+
+	t.Run("NormalReturn", runCase("a, b", big.NewInt(1), big.NewInt(2)))
+	t.Run("EmptyReturn", runCase("", big.NewInt(1), big.NewInt(2)))
+	t.Run("AnotherVariable", runCase("b, c", big.NewInt(2), big.NewInt(3)))
+}