test: Add required tests for go/mysql/collations/charset (#15435)

Signed-off-by: Noble Mittal <noblemittal@outlook.com>

go/mysql/collations/charset/charset_test.go

@@ -0,0 +1,108 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package charset
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsMultibyteByName(t *testing.T) {
+	testCases := []struct {
+		csname string
+		want   bool
+	}{
+		{"euckr", true},
+		{"gb2312", true},
+		{"sjis", true},
+		{"cp932", true},
+		{"eucjpms", true},
+		{"ujis", true},
+		{"utf16", false},
+		{"latin1", false},
+		{"binary", false},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.csname, func(t *testing.T) {
+			assert.Equal(t, tc.want, IsMultibyteByName(tc.csname))
+		})
+	}
+}
+
+func TestIsUnicode(t *testing.T) {
+	testCases := []struct {
+		cs   Charset
+		want bool
+	}{
+		{Charset_utf8mb3{}, true},
+		{Charset_utf8mb4{}, true},
+		{Charset_utf16{}, true},
+		{Charset_utf16le{}, true},
+		{Charset_ucs2{}, true},
+		{Charset_utf32{}, true},
+		{&testCharset1{}, false},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.cs.Name(), func(t *testing.T) {
+			assert.Equal(t, tc.want, IsUnicode(tc.cs))
+		})
+	}
+}
+
+func TestIsUnicodeByName(t *testing.T) {
+	testCases := []struct {
+		csname string
+		want   bool
+	}{
+		{"utf8", true},
+		{"utf8mb3", true},
+		{"utf8mb4", true},
+		{"utf16", true},
+		{"utf16le", true},
+		{"ucs2", true},
+		{"utf32", true},
+		{"binary", false},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.csname, func(t *testing.T) {
+			assert.Equal(t, tc.want, IsUnicodeByName(tc.csname))
+		})
+	}
+}
+
+func TestIsBackslashSafe(t *testing.T) {
+	testCases := []struct {
+		cs   Charset
+		want bool
+	}{
+		{Charset_sjis{}, false},
+		{Charset_cp932{}, false},
+		{Charset_gb18030{}, false},
+		{Charset_utf16le{}, true},
+		{&testCharset1{}, true},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.cs.Name(), func(t *testing.T) {
+			assert.Equal(t, tc.want, IsBackslashSafe(tc.cs))
+		})
+	}
+}