add tests for SafeExec module

services/filestore/test/unit/coffee/SafeExec.coffee

@@ -0,0 +1,42 @@
+assert = require("chai").assert
+sinon = require('sinon')
+chai = require('chai')
+should = chai.should()
+expect = chai.expect
+modulePath = "../../../app/js/SafeExec.js"
+SandboxedModule = require('sandboxed-module')
+
+describe "SafeExec", ->
+
+	beforeEach ->
+
+		@safe_exec = SandboxedModule.require modulePath, requires:
+			"logger-sharelatex":
+				log:->
+				err:->
+		@options = {timeout: 10*1000, killSignal: "SIGTERM" }
+
+	describe "safe_exec", ->
+
+		it "should execute a valid command", (done) ->
+			@safe_exec "/bin/echo hello", @options, (err, stdout, stderr) =>
+				stdout.should.equal "hello\n"
+				should.not.exist(err)
+				done()
+
+		it "should execute a command with non-zero exit status", (done) ->
+			@safe_exec "/bin/false", @options, (err, stdout, stderr) =>
+				stdout.should.equal ""
+				stderr.should.equal ""
+				err.message.should.equal "exit status 1"
+				done()
+
+		it "should handle an invalid command", (done) ->
+			@safe_exec "/bin/foobar", @options, (err, stdout, stderr) =>
+				err.code.should.equal "ENOENT"
+				done()
+
+		it "should handle a command that runs too long", (done) ->
+			@safe_exec "/bin/sleep 10", {timeout: 500, killSignal: "SIGTERM"}, (err, stdout, stderr) =>
+				err.should.equal "SIGTERM"
+				done()