Support turning off node_modules default exclude via flag

index.js

@@ -58,6 +58,7 @@ function NYC (config) {
     cwd: this.cwd,
     include: config.include,
     exclude: config.exclude,
+    excludeNodeModules: config.excludeNodeModules !== false,
     extension: this.extensions
   })
 

lib/config-util.js

@@ -89,6 +89,12 @@ Config.buildYargs = function (cwd) {
       description: 'should exclude logic be performed after the source-map remaps filenames?',
       global: false
     })
+    .option('exclude-node-modules', {
+      default: true,
+      type: 'boolean',
+      describe: 'whether or not to exclude all node_module folders (i.e. **/node_modules/**) by default',
+      global: false
+    })
     .option('include', {
       alias: 'n',
       default: [],

test/src/nyc-tap.js

@@ -123,6 +123,20 @@ describe('nyc', function () {
       nyc.exclude.shouldInstrument('/cwd/foo/bar/__tests__/foo.js', './__tests__/foo.js').should.equal(false)
     })
 
+    it('should allow turning off default node_modules exclude', function () {
+      var nyc = new NYC(configUtil.buildYargs('/cwd').parse([
+        '--exclude-node-modules', 'false',
+        '--exclude=**/__tests__/**',
+        '--exclude=node_modules/**'
+      ]))
+      // For this test, only excluding root node_modules. Local node_modules are allowed, but we
+      // still exclude matching items inside of local node_modules.
+      nyc.exclude.shouldInstrument('/cwd/foo', 'foo').should.equal(true)
+      nyc.exclude.shouldInstrument('/cwd/node_modules/bar', 'node_modules/bar').should.equal(false)
+      nyc.exclude.shouldInstrument('/cwd/foo/node_modules/bar', 'foo/node_modules/bar').should.equal(true)
+      nyc.exclude.shouldInstrument('/cwd/foo/node_modules/bar/__tests__/baz.js', 'foo/node_modules/bar/__tests__/baz.js').should.equal(false)
+    })
+
     it('should exclude appropriately with config.exclude', function () {
       var nyc = new NYC(configUtil.buildYargs(fixtures).parse())