You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: runewidth_test.go
    path of file: ./repos/termdash/private/runewidth
    
    the code of the file until where you have to start completion: // Copyright 2019 Google Inc.
//
// 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 e
    
func TestStringWidth(t *testing.T) {
	tests := []struct {
		desc      string
		str       string
		opts      []Option
		eastAsian bool
		want      int
	}{
		{
			desc: "ascii characters",
			str:  "hello",
			want: 5,
		},
		{
			desc: "override rune widths with an option",
			str:  "hello",
			opts: []Option{
				CountAsWidth('h', 5),
				CountAsWidth('e', 5),
			},
			want: 13,
		},
		{
			desc: "string from mattn/runewidth/runewidth_test",
			str:  "■㈱の世界①",
			want: 10,
		},
		{
			desc:      "string in eastAsian from mattn/runewidth/runewidth_test",
			str:       "■㈱の世界①",
			eastAsian: true,
			want:      12,
		},
		{
			desc: "string using termdash characters",
			str:  "⇄…⇧⇩",
			want: 4,
		},
		{
			desc:      "string in eastAsien using termdash characters",
			str:       "⇄…⇧⇩",
			eastAsian: true,
			want:      4,
		},
	}

	for _, tc := range tests {
		t.Run(tc.desc, func(t *testing.T) {
			runewidth.DefaultCondition.EastAsianWidth = tc.eastAsian
			defer func() {
				runewidth.DefaultCondition.EastAsianWidth = false
			}()

			if got := StringWidth(tc.str, tc.opts...); got != tc.want {
				t.Errorf("StringWidth(%q) => %v, want %v", tc.str, got, tc.want)
			}
		})
	}
}