test: should not crash with 20-thousand files

.gitignore

@@ -1,2 +1,3 @@
 node_modules
-test/build-*
+test/build-*
+test/out

package.json

@@ -35,7 +35,7 @@
   },
   "devDependencies": {
     "assert-dir-equal": "^1.0.1",
-    "metalsmith": "^1.0.1",
+    "metalsmith": "^2.1.0",
     "mocha": "^2.1.0"
   }
 }

test/test.js

@@ -2,6 +2,7 @@ var assert = require('assert');
 var equal = require('assert-dir-equal');
 var Metalsmith = require('metalsmith');
 var pandoc = require('..');
+var fs = require('fs');
 
 describe('metalsmith-pandoc', function(){
   it('should convert markdown files to html', function(done){
@@ -28,4 +29,29 @@ describe('metalsmith-pandoc', function(){
       done();
     });
   });
+
+  it('should be able to process 20 thousand files', function(done){
+    var many = 20000;
+    this.timeout(0);
+
+    Metalsmith('test')
+    .destination('out')
+    .concurrency(1000)  // avoid file table overflow (ENFILE)
+    .use(function (files) {
+      // add fake files
+      for (var i = 0; i < many; i += 1) {
+        var filename = i + '.md';
+        files[filename] = {
+          title: 'fake ' + i,
+          contents: 'sample markdown'
+        };
+      }
+    })
+    .use(pandoc())
+    .build(function(err){
+      if (err) return done(err);
+      assert.equal(fs.readdirSync('test/out').length, many + 1);
+      done();
+    });
+  });
 });