Created a test for too many file descriptors on a file

test/persistence.test.js

@@ -872,6 +872,19 @@ describe('Persistence', function () {
       });
     });
 
+    it.only("Cannot cause EMFILE errors by opening too many file descriptors", function (done) {
+      child_process.execFile('test_lac/openFdsLaunch.sh', function (err, stdout, stderr) {
+        if (err) { return done(err); }
+
+        // The subprocess will not output anything to stdout unless part of the test fails
+        if (stdout.length !== 0) {
+          return done(stdout);
+        } else {
+          return done();
+        }
+      });
+    });
+
   });   // ==== End of 'Prevent dataloss when persisting data' ====
 
 

test_lac/openFds.test.js

@@ -0,0 +1,32 @@
+var fs = require('fs')
+  , child_process = require('child_process')
+  , async = require('async')
+  , N = 64   // One file descriptor too many
+  , i =0
+  ;
+
+function multipleOpen (filename, N, callback) {
+  async.whilst( function () { return i < N; }
+              , function (cb) {
+                fs.open(filename, 'r', function (err, fd) {
+                  i += 1;
+                  return cb(err);
+                });
+              }
+              , callback);
+}
+
+
+async.waterfall([
+  function (cb) {
+    multipleOpen('./test_lac/openFdsTestFile', 2 * N + 1, function (err) {
+      if (!err) { console.log("No error occured while opening a file too many times"); }
+      return cb();
+    })
+  }
+, function (cb) {
+    multipleOpen('./test_lac/openFdsTestFile2', N, function (err) {
+      if (err) { console.log('An unexpected error occured when opening file not too many times: ' + err); }
+    })
+  }
+]);

test_lac/openFdsLaunch.sh

@@ -0,0 +1,2 @@
+ulimit -n 128
+node ./test_lac/openFds.test.js

test_lac/openFdsTestFile

@@ -0,0 +1 @@
+Random stuff

test_lac/openFdsTestFile2

@@ -0,0 +1 @@
+Some other random stuff