fix: add more general support for negated exclude rules

packages/test-exclude/index.js

@@ -32,27 +32,43 @@ function TestExclude (opts) {
     this.include = false
   }
 
-  if (!this.removeNegatedModuleExclude() && this.exclude.indexOf('**/node_modules/**') === -1) {
+  if (this.exclude.indexOf('**/node_modules/**') === -1) {
     this.exclude.push('**/node_modules/**')
   }
 
   this.exclude = prepGlobPatterns(
     [].concat(arrify(this.exclude))
   )
+
+  this.handleNegation()
 }
 
-// if a glob has been provided that explicitly negates
-// the **/node_modules/** default exclude rule, remove it from
-// excludes but don't add the default exclude rule.
-TestExclude.prototype.removeNegatedModuleExclude = function () {
-  var moduleExcludeNegated = false
+// handle the special case of negative globs
+// (!**foo/bar); we create a new this.excludeNegated set
+// of rules, which is applied after excludes and we
+// move excluded include rules into this.excludes.
+TestExclude.prototype.handleNegation = function () {
+  if (Array.isArray(this.include)) {
+    const includeNegated = this.include.filter(function (e) {
+      return e.charAt(0) === '!'
+    }).map(function (e) {
+      return e.slice(1)
+    })
+    this.exclude.push.apply(this.exclude, prepGlobPatterns(includeNegated))
+    this.include = this.include.filter(function (e) {
+      return e.charAt(0) !== '!'
+    })
+  }
+
+  this.excludeNegated = this.exclude.filter(function (e) {
+    return e.charAt(0) === '!'
+  }).map(function (e) {
+    return e.slice(1)
+  })
   this.exclude = this.exclude.filter(function (e) {
-    var negated = !!micromatch('./node_modules/foo.js', e, {nonegate: false}).length !==
-      !!micromatch('./node_modules/foo.js', e, {nonegate: true}).length
-    if (negated) moduleExcludeNegated = true
-    return !negated
+    return e.charAt(0) !== '!'
   })
-  return moduleExcludeNegated
+  this.excludeNegated = prepGlobPatterns(this.excludeNegated)
 }
 
 TestExclude.prototype.shouldInstrument = function (filename, relFile) {
@@ -67,7 +83,11 @@ TestExclude.prototype.shouldInstrument = function (filename, relFile) {
     pathToCheck = relFile.replace(/^\.[\\/]/, '') // remove leading './' or '.\'.
   }
 
-  return (!this.include || micromatch.any(pathToCheck, this.include, {dotfiles: true})) && !micromatch.any(pathToCheck, this.exclude, {dotfiles: true})
+  return (
+    !this.include ||
+    micromatch.any(pathToCheck, this.include, {dotfiles: true})) &&
+    (!micromatch.any(pathToCheck, this.exclude, {dotfiles: true}) ||
+     micromatch.any(pathToCheck, this.excludeNegated, {dotfiles: true}))
 }
 
 TestExclude.prototype.pkgConf = function (key, path) {

packages/test-exclude/test/test-exclude.js

@@ -86,6 +86,32 @@ describe('testExclude', function () {
     e.shouldInstrument('src/foo.js').should.equal(true)
   })
 
+  it('allows negated exclude patterns', function () {
+    const e = exclude({
+      exclude: ['foo/**', '!foo/bar.js']
+    })
+
+    e.shouldInstrument('./foo/fizz.js').should.equal(false)
+    e.shouldInstrument('./foo/bar.js').should.equal(true)
+  })
+
+  it('allows negated include patterns', function () {
+    const e = exclude({
+      include: ['batman/**', '!batman/robin.js']
+    })
+
+    e.shouldInstrument('./batman/joker.js').should.equal(true)
+    e.shouldInstrument('./batman/robin.js').should.equal(false)
+  })
+
+  it('negated exclude patterns unrelated to node_modules do not affect default node_modules exclude behavior', function () {
+    const e = exclude({
+      exclude: ['!foo/**']
+    })
+
+    e.shouldInstrument('node_modules/cat.js').should.equal(false)
+  })
+
   it('exports defaultExclude', function () {
     exclude.defaultExclude.should.deep.equal([
       'coverage/**',