Add visualize tester (#788)

package.json

@@ -49,6 +49,7 @@
 	},
 	"devDependencies": {
 		"@ava/babel": "^1.0.1",
+		"@babel/code-frame": "7.10.3",
 		"@lubien/fixture-beta-package": "^1.0.0-beta.1",
 		"@typescript-eslint/parser": "^3.4.0",
 		"ava": "^3.9.0",

test/consistent-function-scoping.js

@@ -2,6 +2,7 @@ import test from 'ava';
 import avaRuleTester from 'eslint-ava-rule-tester';
 import {outdent} from 'outdent';
 import rule from '../rules/consistent-function-scoping';
+import visualizeRuleTester from './utils/visualize-rule-tester';
 
 const ruleTester = avaRuleTester(test, {
 	parserOptions: {
@@ -647,3 +648,47 @@ typescriptRuleTester.run('consistent-function-scoping', rule, {
 	],
 	invalid: []
 });
+
+const visualizeTester = visualizeRuleTester(test, {
+	parserOptions: {
+		sourceType: 'module',
+		ecmaVersion: 2020,
+		ecmaFeatures: {
+			jsx: true
+		}
+	}
+});
+
+visualizeTester.run('consistent-function-scoping', rule, [
+	outdent`
+		function foo() {
+			function bar() {}
+		}
+	`,
+	outdent`
+		function foo() {
+			async function bar() {}
+		}
+	`,
+	outdent`
+		function foo() {
+			function * bar() {}
+		}
+	`,
+	outdent`
+		function foo() {
+			async function * bar() {}
+		}
+	`,
+	outdent`
+		function foo() {
+			const bar = () => {}
+		}
+	`,
+	'const doFoo = () => bar => bar;',
+	outdent`
+		function foo() {
+			const bar = async () => {}
+		}
+	`
+]);

test/no-useless-undefined.js

@@ -2,6 +2,7 @@ import test from 'ava';
 import {outdent} from 'outdent';
 import avaRuleTester from 'eslint-ava-rule-tester';
 import rule from '../rules/no-useless-undefined';
+import visualizeRuleTester from './utils/visualize-rule-tester';
 
 const messageId = 'no-useless-undefined';
 
@@ -238,3 +239,25 @@ typescriptRuleTester.run('no-useless-undefined', rule, {
 	],
 	invalid: []
 });
+
+const visualizeTester = visualizeRuleTester(test, {
+	parserOptions: {
+		ecmaVersion: 2020
+	}
+});
+
+visualizeTester.run('no-useless-undefined', rule, [
+	outdent`
+		foo(
+			undefined,
+			bar,
+			undefined,
+			undefined,
+			undefined,
+			undefined,
+		)
+	`,
+	'function foo([bar = undefined] = []) {}',
+	'foo(bar, undefined, undefined);',
+	'let a = undefined, b = 2;'
+]);

test/snapshots/consistent-function-scoping.js.md

@@ -0,0 +1,80 @@
+# Snapshot report for `test/consistent-function-scoping.js`
+
+The actual snapshot is saved in `consistent-function-scoping.js.snap`.
+
+Generated by [AVA](https://avajs.dev).
+
+## consistent-function-scoping - #1
+
+> Snapshot 1
+
+    `␊
+      1 | function foo() {␊
+    > 2 | 	function bar() {}␊
+        | 	^^^^^^^^^^^^ Move function 'bar' to the outer scope.␊
+      3 | }␊
+    `
+
+## consistent-function-scoping - #2
+
+> Snapshot 1
+
+    `␊
+      1 | function foo() {␊
+    > 2 | 	async function bar() {}␊
+        | 	^^^^^^^^^^^^^^^^^^ Move async function 'bar' to the outer scope.␊
+      3 | }␊
+    `
+
+## consistent-function-scoping - #3
+
+> Snapshot 1
+
+    `␊
+      1 | function foo() {␊
+    > 2 | 	function * bar() {}␊
+        | 	^^^^^^^^^^^^^^ Move generator function 'bar' to the outer scope.␊
+      3 | }␊
+    `
+
+## consistent-function-scoping - #4
+
+> Snapshot 1
+
+    `␊
+      1 | function foo() {␊
+    > 2 | 	async function * bar() {}␊
+        | 	^^^^^^^^^^^^^^^^^^^^ Move async generator function 'bar' to the outer scope.␊
+      3 | }␊
+    `
+
+## consistent-function-scoping - #5
+
+> Snapshot 1
+
+    `␊
+      1 | function foo() {␊
+    > 2 | 	const bar = () => {}␊
+        | 	               ^^ Move arrow function 'bar' to the outer scope.␊
+      3 | }␊
+    `
+
+## consistent-function-scoping - #6
+
+> Snapshot 1
+
+    `␊
+    > 1 | const doFoo = () => bar => bar;␊
+        |                         ^^ Move arrow function to the outer scope.␊
+    `
+
+## consistent-function-scoping - #7
+
+> Snapshot 1
+
+    `␊
+      1 | function foo() {␊
+    > 2 | 	const bar = async () => {}␊
+        | 	                     ^^ Move async arrow function 'bar' to the outer scope.␊
+      3 | }␊
+    `

test/snapshots/no-useless-undefined.js.md

@@ -0,0 +1,51 @@
+# Snapshot report for `test/no-useless-undefined.js`
+
+The actual snapshot is saved in `no-useless-undefined.js.snap`.
+
+Generated by [AVA](https://avajs.dev).
+
+## no-useless-undefined - #1
+
+> Snapshot 1
+
+    `␊
+      1 | foo(␊
+      2 | 	undefined,␊
+      3 | 	bar,␊
+    > 4 | 	undefined,␊
+        | 	^^^^^^^^^^␊
+    > 5 | 	undefined,␊
+        | ^^^^^^^^^^^␊
+    > 6 | 	undefined,␊
+        | ^^^^^^^^^^^␊
+    > 7 | 	undefined,␊
+        | ^^^^^^^^^^^ Do not use useless `undefined`.␊
+      8 | )␊
+    `
+
+## no-useless-undefined - #2
+
+> Snapshot 1
+
+    `␊
+    > 1 | function foo([bar = undefined] = []) {}␊
+        |                     ^^^^^^^^^ Do not use useless `undefined`.␊
+    `
+
+## no-useless-undefined - #3
+
+> Snapshot 1
+
+    `␊
+    > 1 | foo(bar, undefined, undefined);␊
+        |          ^^^^^^^^^^^^^^^^^^^^ Do not use useless `undefined`.␊
+    `
+
+## no-useless-undefined - #4
+
+> Snapshot 1
+
+    `␊
+    > 1 | let a = undefined, b = 2;␊
+        |         ^^^^^^^^^ Do not use useless `undefined`.␊
+    `

test/utils/visualize-rule-tester.js

@@ -0,0 +1,78 @@
+'use strict';
+const {Linter} = require('eslint');
+const {codeFrameColumns} = require('@babel/code-frame');
+const codeFrameColumnsOptions = {linesAbove: Infinity, linesBelow: Infinity};
+
+function visualizeRange(text, location, message) {
+	return codeFrameColumns(
+		text,
+		location,
+		{
+			...codeFrameColumnsOptions,
+			message
+		}
+	);
+}
+
+function visualizeEslintResult(text, result) {
+	const {line, column, endLine, endColumn, message} = result;
+	const location = {
+		start: {
+			line,
+			column
+		}
+	};
+
+	if (typeof endLine === 'number' && typeof endColumn === 'number') {
+		location.end = {
+			line: endLine,
+			column: endColumn
+		};
+	}
+
+	return `\n${visualizeRange(text, location, message)}\n`;
+}
+
+class VisualizeRuleTester {
+	constructor(test, config) {
+		this.test = test;
+		this.config = config;
+	}
+
+	run(ruleId, rule, tests) {
+		const {test, config} = this;
+		const linter = new Linter();
+		const verifyConfig = {
+			...config,
+			rules: {
+				[ruleId]: 'error'
+			}
+		};
+
+		linter.defineRule(ruleId, rule);
+
+		for (const [index, code] of tests.entries()) {
+			test(`${ruleId} - #${index + 1}`, t => {
+				const results = linter.verify(code, verifyConfig);
+
+				if (results.length !== 1) {
+					throw new Error('Visualize test should has exactly one error.');
+				}
+
+				const [error] = results;
+
+				if (error.fatal) {
+					throw new Error(error.message);
+				}
+
+				t.snapshot(visualizeEslintResult(code, error));
+			});
+		}
+	}
+}
+
+function visualizeRuleTester(test, config) {
+	return new VisualizeRuleTester(test, config);
+}
+
+module.exports = visualizeRuleTester;