1 files changed, 104 insertions, 0 deletions
diff --git a/src/database/sql/convert_test.go b/src/database/sql/convert_test.go
index 412f0b1823..8a82891c25 100644
--- a/src/database/sql/convert_test.go
+++ b/src/database/sql/convert_test.go
@@ -494,3 +494,107 @@ func TestDriverArgs(t *testing.T) {
 		}
 	}
 }
+
+type dec struct {
+	form        byte
+	neg         bool
+	coefficient [16]byte
+	exponent    int32
+}
+
+func (d dec) Decompose(buf []byte) (form byte, negative bool, coefficient []byte, exponent int32) {
+	coef := make([]byte, 16)
+	copy(coef, d.coefficient[:])
+	return d.form, d.neg, coef, d.exponent
+}
+
+func (d *dec) Compose(form byte, negative bool, coefficient []byte, exponent int32) error {
+	switch form {
+	default:
+		return fmt.Errorf("unknown form %d", form)
+	case 1, 2:
+		d.form = form
+		d.neg = negative
+		return nil
+	case 0:
+	}
+	d.form = form
+	d.neg = negative
+	d.exponent = exponent
+
+	// This isn't strictly correct, as the extra bytes could be all zero,
+	// ignore this for this test.
+	if len(coefficient) > 16 {
+		return fmt.Errorf("coefficent too large")
+	}
+	copy(d.coefficient[:], coefficient)
+
+	return nil
+}
+
+type decFinite struct {
+	neg         bool
+	coefficient [16]byte
+	exponent    int32
+}
+
+func (d decFinite) Decompose(buf []byte) (form byte, negative bool, coefficient []byte, exponent int32) {
+	coef := make([]byte, 16)
+	copy(coef, d.coefficient[:])
+	return 0, d.neg, coef, d.exponent
+}
+
+func (d *decFinite) Compose(form byte, negative bool, coefficient []byte, exponent int32) error {
+	switch form {
+	default:
+		return fmt.Errorf("unknown form %d", form)
+	case 1, 2:
+		return fmt.Errorf("unsupported form %d", form)
+	case 0:
+	}
+	d.neg = negative
+	d.exponent = exponent
+
+	// This isn't strictly correct, as the extra bytes could be all zero,
+	// ignore this for this test.
+	if len(coefficient) > 16 {
+		return fmt.Errorf("coefficent too large")
+	}
+	copy(d.coefficient[:], coefficient)
+
+	return nil
+}
+
+func TestDecimal(t *testing.T) {
+	list := []struct {
+		name string
+		in   decimalDecompose
+		out  dec
+		err  bool
+	}{
+		{name: "same", in: dec{exponent: -6}, out: dec{exponent: -6}},
+
+		// Ensure reflection is not used to assign the value by using different types.
+		{name: "diff", in: decFinite{exponent: -6}, out: dec{exponent: -6}},
+
+		{name: "bad-form", in: dec{form: 200}, err: true},
+	}
+	for _, item := range list {
+		t.Run(item.name, func(t *testing.T) {
+			out := dec{}
+			err := convertAssign(&out, item.in)
+			if item.err {
+				if err == nil {
+					t.Fatalf("unexpected nil error")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if !reflect.DeepEqual(out, item.out) {
+				t.Fatalf("got %#v want %#v", out, item.out)
+			}
+		})
+	}
+}