Remove special case for exp == 1

Generalize tests

numeric.go

@@ -448,11 +448,8 @@ func (src *Numeric) toFloat64() (float64, error) {
 		return math.Inf(-1), nil
 	}
 
-	switch {
-	case src.Exp == 0:
+	if src.Exp == 0 {
 		return float64(src.Int.Int64()), nil
-	case src.Exp == 1:
-		return float64(src.Int.Int64() * 10), nil
 	}
 
 	buf := make([]byte, 0, 32)

numeric_test.go

@@ -445,20 +445,23 @@ func TestNumericSmallNegativeValues(t *testing.T) {
 }
 
 // https://github.com/jackc/pgtype/issues/210
-func TestNumericFloat64(t *testing.T) {
-	n := pgtype.Numeric{
-		Int:    big.NewInt(5),
-		Exp:    1,
-		Status: pgtype.Present,
-	}
+func TestNumericFloat64FromIntegers(t *testing.T) {
+	for i := 0; i < 1024; i++ {
+		n := pgtype.Numeric{
+			Int:    big.NewInt(int64(i)),
+			Exp:    0,
+			Status: pgtype.Present,
+		}
 
-	var f float64
-	err := n.AssignTo(&f)
-	if err != nil {
-		t.Fatal(err)
-	}
+		var got float64
+		err := n.AssignTo(&got)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	if f != 50.0 {
-		t.Fatalf("expected %s, got %f", "50", f)
+		want := float64(i)
+		if got != want {
+			t.Fatalf("expected %d, got %f", i, got)
+		}
 	}
 }