Fix call getNumFmtID with builtInNumFmt return -1

Author: Dokiy

styles.go

@@ -2229,12 +2229,12 @@ func (f *File) newFont(style *Style) *xlsxFont {
 // If given number format code is not exist, will return -1.
 func getNumFmtID(styleSheet *xlsxStyleSheet, style *Style) (numFmtID int) {
 	numFmtID = -1
-	if styleSheet.NumFmts == nil {
-		return
-	}
 	if _, ok := builtInNumFmt[style.NumFmt]; ok {
 		return style.NumFmt
 	}
+	if styleSheet.NumFmts == nil {
+		return
+	}
 	if fmtCode, ok := currencyNumFmt[style.NumFmt]; ok {
 		for _, numFmt := range styleSheet.NumFmts.NumFmt {
 			if numFmt.FormatCode == fmtCode {

styles_test.go

@@ -330,3 +330,18 @@ func TestThemeColor(t *testing.T) {
 		assert.Equal(t, clr[0], clr[1])
 	}
 }
+
+func TestGetNumFmtID(t *testing.T) {
+	f := NewFile()
+
+	fs1, err := parseFormatStyleSet(`{"protection":{"hidden":false,"locked":false},"number_format":10}`)
+	assert.NoError(t, err)
+	id1 := getNumFmtID(&xlsxStyleSheet{}, fs1)
+
+	fs2, err := parseFormatStyleSet(`{"protection":{"hidden":false,"locked":false},"number_format":0}`)
+	assert.NoError(t, err)
+	id2 := getNumFmtID(&xlsxStyleSheet{}, fs2)
+
+	assert.NotEqual(t, id1, id2)
+	assert.NoError(t, f.SaveAs(filepath.Join("test", "TestStyleNumFmt.xlsx")))
+}