prefer-string-slice.js

import test from 'ava';
import avaRuleTester from 'eslint-ava-rule-tester';
import {outdent} from 'outdent';
import rule from '../rules/prefer-string-slice';

const ruleTester = avaRuleTester(test, {
	env: {
		es6: true
	}
});

const typescriptRuleTester = avaRuleTester(test, {
	parser: require.resolve('@typescript-eslint/parser')
});

const errors = [
	{
		ruleId: 'prefer-string-slice'
	}
];

ruleTester.run('prefer-string-slice', rule, {
	valid: [
		'const substr = foo.substr',
		'const substring = foo.substring',

		'foo.slice()',
		'foo.slice(0)',
		'foo.slice(1, 2)',
		'foo.slice(-3, -2)'
	],

	invalid: [
		{
			code: 'foo.substr()',
			output: 'foo.slice()',
			errors
		},
		{
			code: '"foo".substr()',
			output: '"foo".slice()',
			errors
		},
		{
			code: '"foo".substr(1)',
			output: '"foo".slice(1)',
			errors
		},
		{
			code: '"foo".substr(1, 2)',
			output: '"foo".slice(1, 3)',
			errors
		},
		{
			code: '"foo".substr(1, length)',
			output: '"foo".substr(1, length)',
			errors
		},
		{
			code: '"foo".substr(1, "abc".length)',
			output: '"foo".slice(1, 1 + "abc".length)',
			errors
		},
		{
			code: '"foo".substr("1", 2)',
			output: '"foo".substr("1", 2)',
			errors
		},
		{
			code: outdent`
				const length = 123;
				"foo".substr(1, length)
			`,
			output: outdent`
				const length = 123;
				"foo".substr(1, length)
			`,
			errors
		},
		{
			code: outdent`
				const length = 123;
				"foo".substr(0, length)
			`,
			output: outdent`
				const length = 123;
				"foo".slice(0, Math.max(0, length))
			`,
			errors
		},
		{
			code: outdent`
				const length = 123;
				"foo".substr('0', length)
			`,
			output: outdent`
				const length = 123;
				"foo".substr('0', length)
			`,
			errors
		},
		{
			code: '"foo".substr(0, -1)',
			output: '"foo".slice(0, 0)',
			errors
		},
		{
			code: '"foo".substr(0, "foo".length)',
			output: '"foo".slice(0, "foo".length)',
			errors
		},
		{
			code: outdent`
				const length = 123;
				"foo".substr(1, length - 4)
			`,
			output: outdent`
				const length = 123;
				"foo".substr(1, length - 4)
			`,
			errors
		},
		{
			code: outdent`
				const uri = 'foo';
				(uri || '').substr(1)
			`,
			output: outdent`
				const uri = 'foo';
				(uri || '').slice(1)
			`,
			errors
		},

		{
			code: 'foo.substr(start)',
			errors
		},
		{
			code: '"foo".substr(1)',
			errors
		},
		{
			code: 'foo.substr(start, length)',
			errors
		},
		{
			code: '"foo".substr(1, 2)',
			errors
		},
		// Extra arguments
		{
			code: 'foo.substr(1, 2, 3)',
			output: 'foo.substr(1, 2, 3)',
			errors
		},
		// #700
		{
			code: '"Sample".substr(0, "Sample".lastIndexOf("/"))',
			output: '"Sample".slice(0, Math.max(0, "Sample".lastIndexOf("/")))',
			errors
		},

		{
			code: 'foo.substring()',
			output: 'foo.slice()',
			errors
		},
		{
			code: '"foo".substring()',
			output: '"foo".slice()',
			errors
		},
		{
			code: '"foo".substring(1)',
			output: '"foo".slice(1)',
			errors
		},
		{
			code: '"foo".substring(1, 2)',
			output: '"foo".slice(1, 2)',
			errors
		},
		{
			code: '"foo".substring(2, 1)',
			output: '"foo".slice(1, 2)',
			errors
		},
		{
			code: '"foo".substring(-1, -5)',
			output: '"foo".slice(0, 0)',
			errors
		},
		{
			code: '"foo".substring(-1, 2)',
			output: '"foo".slice(0, 2)',
			errors
		},
		{
			code: '"foo".substring(length)',
			output: '"foo".slice(Math.max(0, length))',
			errors
		},
		{
			code: '"foo".substring("fo".length)',
			output: '"foo".slice("fo".length)',
			errors
		},
		{
			code: '"foo".substring(0, length)',
			output: '"foo".slice(0, Math.max(0, length))',
			errors
		},
		{
			code: '"foo".substring(length, 0)',
			output: '"foo".slice(0, Math.max(0, length))',
			errors
		},

		{
			code: 'foo.substring(start)',
			errors
		},
		{
			code: '"foo".substring(1)',
			errors
		},
		{
			code: 'foo.substring(start, end)',
			errors
		},
		{
			code: '"foo".substring(1, 3)',
			errors
		},
		// Extra arguments
		{
			code: 'foo.substring(1, 2, 3)',
			output: 'foo.substring(1, 2, 3)',
			errors
		}
	]
});

typescriptRuleTester.run('prefer-string-slice', rule, {
	valid: [],
	invalid: [
		{
			code: outdent`
				function foo() {
					return (bar as string).substr(3);
				}
			`,
			output: outdent`
				function foo() {
					return (bar as string).slice(3);
				}
			`,
			errors
		},
		{
			code: outdent`
				function foo() {
					return (bar as string).substring(3);
				}
			`,
			output: outdent`
				function foo() {
					return (bar as string).slice(3);
				}
			`,
			errors
		}
	]
});