fix: detect duplicate redundant braces in pattern

lib/validateBraces.js

@@ -17,8 +17,8 @@ import { incorrectBraces } from './messages.js'
  * braces from user configuration, but this is left to the user (after seeing the warning).
  *
  * @example <caption>Globs with brace expansions</caption>
- * - *.{js,tx}         // expanded as *.js, *.ts
- * - *.{{j,t}s,css}    // expanded as *.js, *.ts, *.css
+ * - *.{js,tx}        // expanded as *.js, *.ts
+ * - *.{{j,t}s,css}   // expanded as *.js, *.ts, *.css
  * - file_{1..10}.css  // expanded as file_1.css, file_2.css, …, file_10.css
  *
  * @example <caption>Globs with incorrect brace expansions</caption>
@@ -28,17 +28,17 @@ import { incorrectBraces } from './messages.js'
  * - *.${js}      // dollar-sign inhibits expansion, so treated literally
  * - *.{js\,ts}   // the comma is escaped, so treated literally
  */
-export const BRACES_REGEXP = /(?<![\\$])({)(?:(?!(?<!\\),|\.\.|\{|\}).)*?(?<!\\)(})/g
+export const INCORRECT_BRACES_REGEXP = /(?<![\\$])({)(?:(?!(?<!\\),|\.\.|\{|\}).)*?(?<!\\)(})/g
 
 /**
  * @param {string} pattern
  * @returns {string}
  */
-const withoutIncorrectBraces = (pattern) => {
+const stripIncorrectBraces = (pattern) => {
   let output = `${pattern}`
   let match = null
 
-  while ((match = BRACES_REGEXP.exec(pattern))) {
+  while ((match = INCORRECT_BRACES_REGEXP.exec(pattern))) {
     const fullMatch = match[0]
     const withoutBraces = fullMatch.replace(/{/, '').replace(/}/, '')
     output = output.replace(fullMatch, withoutBraces)
@@ -47,6 +47,30 @@ const withoutIncorrectBraces = (pattern) => {
   return output
 }
 
+/**
+ * This RegExp matches "duplicate" opening and closing braces, without any other braces
+ * in between, where the duplication is redundant and should be removed.
+ *
+ * @example *.{{js,ts}}  // should just be *.{js,ts}
+ */
+export const DOUBLE_BRACES_REGEXP = /{{[^}{]*}}/
+
+/**
+ * @param {string} pattern
+ * @returns {string}
+ */
+const stripDoubleBraces = (pattern) => {
+  let output = `${pattern}`
+  const match = DOUBLE_BRACES_REGEXP.exec(pattern)?.[0]
+
+  if (match) {
+    const withoutBraces = match.replace('{{', '{').replace('}}', '}')
+    output = output.replace(match, withoutBraces)
+  }
+
+  return output
+}
+
 /**
  * Validate and remove incorrect brace expansions from glob pattern.
  * For example `*.{js}` is incorrect because it doesn't contain a `,` or `..`,
@@ -57,7 +81,7 @@ const withoutIncorrectBraces = (pattern) => {
  * @returns {string}
  */
 export const validateBraces = (pattern, logger) => {
-  const fixedPattern = withoutIncorrectBraces(pattern)
+  const fixedPattern = stripDoubleBraces(stripIncorrectBraces(pattern))
 
   if (fixedPattern !== pattern) {
     logger.warn(incorrectBraces(pattern, fixedPattern))

test/unit/validateBraces.spec.js

@@ -1,46 +1,64 @@
 import makeConsoleMock from 'consolemock'
 
-import { validateBraces, BRACES_REGEXP } from '../../lib/validateBraces.js'
+import {
+  validateBraces,
+  INCORRECT_BRACES_REGEXP,
+  DOUBLE_BRACES_REGEXP,
+} from '../../lib/validateBraces.js'
 
-describe('BRACES_REGEXP', () => {
+describe('INCORRECT_BRACES_REGEXP', () => {
   it(`should match '*.{js}'`, () => {
-    expect('*.{js}'.match(BRACES_REGEXP)).toBeTruthy()
+    expect('*.{js}'.match(INCORRECT_BRACES_REGEXP)).toBeTruthy()
   })
 
   it(`should match 'file_{10}'`, () => {
-    expect('file_{test}'.match(BRACES_REGEXP)).toBeTruthy()
+    expect('file_{test}'.match(INCORRECT_BRACES_REGEXP)).toBeTruthy()
   })
 
   it(`should match '*.{spec\\.js}'`, () => {
-    expect('*.{spec\\.js}'.match(BRACES_REGEXP)).toBeTruthy()
+    expect('*.{spec\\.js}'.match(INCORRECT_BRACES_REGEXP)).toBeTruthy()
   })
 
   it(`should match '*.{js\\,ts}'`, () => {
-    expect('*.{js\\,ts}'.match(BRACES_REGEXP)).toBeTruthy()
+    expect('*.{js\\,ts}'.match(INCORRECT_BRACES_REGEXP)).toBeTruthy()
   })
 
   it("should not match '*.${js}'", () => {
-    expect('*.${js}'.match(BRACES_REGEXP)).not.toBeTruthy()
+    expect('*.${js}'.match(INCORRECT_BRACES_REGEXP)).toBeFalsy()
   })
 
   it(`should not match '.{js,ts}'`, () => {
-    expect('.{js,ts}'.match(BRACES_REGEXP)).not.toBeTruthy()
+    expect('.{js,ts}'.match(INCORRECT_BRACES_REGEXP)).toBeFalsy()
   })
 
   it(`should not match 'file_{1..10}'`, () => {
-    expect('file_{1..10}'.match(BRACES_REGEXP)).not.toBeTruthy()
+    expect('file_{1..10}'.match(INCORRECT_BRACES_REGEXP)).toBeFalsy()
   })
 
   it(`should not match '*.\\{js\\}'`, () => {
-    expect('*.\\{js\\}'.match(BRACES_REGEXP)).not.toBeTruthy()
+    expect('*.\\{js\\}'.match(INCORRECT_BRACES_REGEXP)).toBeFalsy()
   })
 
   it(`should not match '*.\\{js}'`, () => {
-    expect('*.\\{js}'.match(BRACES_REGEXP)).not.toBeTruthy()
+    expect('*.\\{js}'.match(INCORRECT_BRACES_REGEXP)).toBeFalsy()
   })
 
   it(`should not match '*.{js\\}'`, () => {
-    expect('*.{js\\}'.match(BRACES_REGEXP)).not.toBeTruthy()
+    expect('*.{js\\}'.match(INCORRECT_BRACES_REGEXP)).toBeFalsy()
+  })
+})
+
+describe('DOUBLE_BRACES_REGEXP', () => {
+  it(`should match '*.{{js,ts}}'`, () => {
+    expect('*.{{js,ts}}'.match(DOUBLE_BRACES_REGEXP)).toBeTruthy()
+  })
+
+  it(`should not match '*.{{js,ts},{css}}'`, () => {
+    expect('*.{{js,ts},{css}}'.match(DOUBLE_BRACES_REGEXP)).toBeFalsy()
+  })
+
+  it(`should not match '*.{{js,ts},{css}}'`, () => {
+    expect('*.{{js,ts},{css}}'.match(DOUBLE_BRACES_REGEXP)).toBeFalsy()
   })
 })
 
@@ -84,18 +102,15 @@ describe('validateBraces', () => {
     `)
   })
 
-  /**
-   * @todo This isn't correctly detected even though the outer braces are invalid.
-   */
-  it.skip('should warn about `*.{{js,ts}}` and return fixed pattern', () => {
+  it('should warn about `*.{{js,ts}}` and return fixed pattern', () => {
     const logger = makeConsoleMock()
 
     const fixedBraces = validateBraces('*.{{js,ts}}', logger)
 
     expect(fixedBraces).toEqual('*.{js,ts}')
     expect(logger.printHistory()).toMatchInlineSnapshot(`
       "
-      WARN ‼ Detected incorrect braces with only single value: \`*.{{js,ts}}\`. Reformatted as: \`*.{js,ts}\`
+      WARN ⚠ Detected incorrect braces with only single value: \`*.{{js,ts}}\`. Reformatted as: \`*.{js,ts}\`
       "
     `)
   })