Use snapshots in rule tests (#709)

* Use snapshots in rule tests

* Relative file name

* Removed unused rule tester file

* Update tools and docs

Author: RunDevelopment

CONTRIBUTING.md

@@ -56,9 +56,9 @@ The following steps will walk you through the process of creating a new rule.
 
 1. Test your rule:
 
-    Add test for every feature and option of your rule. (We use [ESLint's `RuleTester`](https://eslint.org/docs/developer-guide/nodejs-api#ruletester) for testing rules.)
+    Add test for every feature and option of your rule. We use a snapshot-based rule tester for testing rules.
 
-    Use `npm test` to run all tests.
+    Use `npm test` to run all tests. Use `npm run test:update` to update snapshots.
 
 1. Document your rule:
 

package-lock.json

@@ -22,6 +22,7 @@
         "test": "npm run test:nyc",
         "test:nyc": "nyc --reporter=lcov npm run test:base",
         "test:watch": "npm run test:base -- --watch",
+        "test:update": "npm run test:base -- --update",
         "update": "ts-node --transpile-only ./tools/update.ts && npm run eslint-fix && npm run update:eslint-docs",
         "update:eslint-docs": "npm run build && eslint-doc-generator",
         "new": "ts-node ./tools/new-rule.ts",
@@ -86,6 +87,7 @@
         "eslint-plugin-regexp": "~2.3.0",
         "eslint-plugin-vue": "^9.0.0",
         "eslint-plugin-yml": "^1.0.0",
+        "eslint-snapshot-rule-tester": "^0.1.0",
         "intl-segmenter-polyfill": "^0.4.4",
         "markdownlint-cli": "^0.39.0",
         "mocha": "^10.0.0",

package.json

@@ -0,0 +1,28 @@
+# eslint-snapshot-rule-tester format: v1
+
+
+Test: confusing-quantifier >> invalid
+Code:
+  1 | /(a?){5}/
+    |      ^~~ [1]
+
+[1] This quantifier is confusing because its minimum is 5 but it can match the empty string. Maybe replace it with `{0,5}` to reflect that it can match the empty string?
+---
+
+
+Test: confusing-quantifier >> invalid
+Code:
+  1 | /(?:a?b*|c+){4}/
+    |             ^~~ [1]
+
+[1] This quantifier is confusing because its minimum is 4 but it can match the empty string. Maybe replace it with `{0,4}` to reflect that it can match the empty string?
+---
+
+
+Test: confusing-quantifier >> invalid
+Code:
+  1 | /[\q{a|}]+/v
+    |          ^ [1]
+
+[1] This quantifier is confusing because its minimum is 1 but it can match the empty string. Maybe replace it with `*` to reflect that it can match the empty string?
+---

tests/lib/rule-tester.ts

@@ -0,0 +1,153 @@
+# eslint-snapshot-rule-tester format: v1
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 | /\x00/
+    |  ^~~~ [1]
+
+Output:
+  1 | /\0/
+
+[1] Unexpected control character escape '\x00' (U+0000). Use '\0' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 | /\x0a/
+    |  ^~~~ [1]
+
+Output:
+  1 | /\n/
+
+[1] Unexpected control character escape '\x0a' (U+000a). Use '\n' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 | /\cJ/
+    |  ^~~ [1]
+
+Output:
+  1 | /\n/
+
+[1] Unexpected control character escape '\cJ' (U+000a). Use '\n' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 | /\u{a}/u
+    |  ^~~~~ [1]
+
+Output:
+  1 | /\n/u
+
+[1] Unexpected control character escape '\u{a}' (U+000a). Use '\n' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 | RegExp("\\cJ")
+    |         ^~~~ [1]
+
+Output:
+  1 | RegExp("\\n")
+
+[1] Unexpected control character escape '\cJ' (U+000a). Use '\n' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 | RegExp("\\u{a}", "u")
+    |         ^~~~~~ [1]
+
+Output:
+  1 | RegExp("\\n", "u")
+
+[1] Unexpected control character escape '\u{a}' (U+000a). Use '\n' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 | /\u0009/
+    |  ^~~~~~ [1]
+
+Output:
+  1 | /\t/
+
+[1] Unexpected control character escape '\u0009' (U+0009). Use '\t' instead.
+---
+
+
+Test: control-character-escape >> invalid >>> /\u0009/ 2
+Code:
+  1 | /	/
+    |  ^ [1]
+
+Output:
+  1 | /\t/
+
+[1] Unexpected control character escape '	' (U+0009). Use '\t' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 |
+  2 |             const s = "\\u0009"
+    |                        ^~~~~~~ [1]
+  3 |             new RegExp(s)
+  4 |             
+
+Output:
+  1 |
+  2 |             const s = "\\t"
+  3 |             new RegExp(s)
+  4 |             
+
+[1] Unexpected control character escape '\u0009' (U+0009). Use '\t' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 |
+  2 |             const s = "\\u"+"0009"
+    |                       ^~~~~~~~~~~~ [1]
+  3 |             new RegExp(s)
+  4 |             
+
+Output: unchanged
+
+[1] Unexpected control character escape '\u0009' (U+0009). Use '\t' instead.
+---
+
+
+Test: control-character-escape >> invalid >>> RegExp("\t\r\n\0" + /\u0009/.source)
+Code:
+  1 | RegExp("\t\r\n\0" + /	/.source)
+    |                      ^ [1]
+
+Output:
+  1 | RegExp("\t\r\n\0" + /\t/.source)
+
+[1] Unexpected control character escape '	' (U+0009). Use '\t' instead.
+---
+
+
+Test: control-character-escape >> invalid
+Code:
+  1 | /[\q{\x00}]/v
+    |      ^~~~ [1]
+
+Output:
+  1 | /[\q{\0}]/v
+
+[1] Unexpected control character escape '\x00' (U+0000). Use '\0' instead.
+---

tests/lib/rules/__snapshots__/confusing-quantifier.ts.eslintsnap

@@ -0,0 +1,41 @@
+# eslint-snapshot-rule-tester format: v1
+
+
+Test: grapheme-string-literal >> invalid
+Code:
+  1 | /[\q{abc}]/v
+    |      ^~~ [1]
+
+[1] Only single characters and graphemes are allowed inside character classes. Use regular alternatives (e.g. `(?:abc|[...])`) for strings instead.
+---
+
+
+Test: grapheme-string-literal >> invalid
+Code:
+  1 | /[\q{a|bc|}]/v
+    |        ^~ [1]
+
+[1] Only single characters and graphemes are allowed inside character classes. Use regular alternatives (e.g. `(?:bc|[...])`) for strings instead.
+---
+
+
+Test: grapheme-string-literal >> invalid
+Code:
+  1 | /[\q{🇦🇨🇦🇩}]/v
+    |      ^~~~~~~~ [1]
+
+[1] Only single characters and graphemes are allowed inside character classes. Use regular alternatives (e.g. `(?:🇦🇨🇦🇩|[...])`) for strings instead.
+---
+
+
+Test: grapheme-string-literal >> invalid
+Code:
+  1 | /[\q{abc|def|ghi|j|k|lm|n}]/v
+    |      ^~~ ^~~ ^~~     ^~
+    |      [1] [2] [3]     [4]
+
+[1] Only single characters and graphemes are allowed inside character classes. Use regular alternatives (e.g. `(?:abc|def|ghi|lm|[...])`) for strings instead.
+[2] Only single characters and graphemes are allowed inside character classes. Use regular alternatives (e.g. `(?:abc|def|ghi|lm|[...])`) for strings instead.
+[3] Only single characters and graphemes are allowed inside character classes. Use regular alternatives (e.g. `(?:abc|def|ghi|lm|[...])`) for strings instead.
+[4] Only single characters and graphemes are allowed inside character classes. Use regular alternatives (e.g. `(?:abc|def|ghi|lm|[...])`) for strings instead.
+---