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: regexp_test.go
    path of file: ./repos/mux
    
    the code of the file until where you have to start completion: package mux

import (
	"net/url"
	"reflect"
	"strconv"
	"testing"
)

func Test_findFirstQueryKey(t *testing.T) {
	tests := []string{
		"a=1&b=2",
		"a=1&a=2&a=banana",
		"ascii=%3Ckey%3A+0x90%3E",
		"a=1;b=2",
		"a=1&a=2;a=banana",
		"a==",
		"a=%2",
		"a=20&%20%3F&=%23+%25%21%3C%3E%23%22%7B%7D%7C%5C%5E%5B%5D%60%E2%98%BA%09:%2F@$%27%28%2
    
func Test_findFirstQueryKey(t *testing.T) {
	tests := []string{
		"a=1&b=2",
		"a=1&a=2&a=banana",
		"ascii=%3Ckey%3A+0x90%3E",
		"a=1;b=2",
		"a=1&a=2;a=banana",
		"a==",
		"a=%2",
		"a=20&%20%3F&=%23+%25%21%3C%3E%23%22%7B%7D%7C%5C%5E%5B%5D%60%E2%98%BA%09:%2F@$%27%28%29%2A%2C%3B&a=30",
		"a=1& ?&=#+%!<>#\"{}|\\^[]`â˜º\t:/@$'()*,;&a=5",
		"a=xxxxxxxxxxxxxxxx&b=YYYYYYYYYYYYYYY&c=ppppppppppppppppppp&f=ttttttttttttttttt&a=uuuuuuuuuuuuu",
	}
	for _, query := range tests {
		t.Run(query, func(t *testing.T) {
			// Check against url.ParseQuery, ignoring the error.
			all, _ := url.ParseQuery(query)
			for key, want := range all {
				t.Run(key, func(t *testing.T) {
					got, ok := findFirstQueryKey(query, key)
					if !ok {
						t.Error("Did not get expected key", key)
					}
					if !reflect.DeepEqual(got, want[0]) {
						t.Errorf("findFirstQueryKey(%s,%s) = %v, want %v", query, key, got, want[0])
					}
				})
			}
		})
	}
}