function createTestFile() {
	return [
		'/*',
		'* @license Apache-2.0',
		'*',
		'* Copyright (c) {{year}} The Stdlib 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.',
		'*/',
		'',
		'/* eslint-disable @typescript-eslint/no-unused-expressions */',
		'',
		'import ns = require( \'./index\' );',
		'',
		'',
		'// TESTS //',
		'',
		'// The exported value is the expected interface...',
		'{',
		'	ns; // $ExpectType Namespace',
		'}',
		''
	].join( '\n' );
}
Returns contents of a `test.ts` file for the chosen namespace.

@private
@returns {string} `test.ts` contents