diff --git a/services/web/test/acceptance/coffee/ProjectStructureMongoLockTest.coffee b/services/web/test/acceptance/coffee/ProjectStructureMongoLockTest.coffee
new file mode 100644
index 0000000000..298d1ea68d
--- /dev/null
+++ b/services/web/test/acceptance/coffee/ProjectStructureMongoLockTest.coffee
@@ -0,0 +1,84 @@
+APP_PATH = "../../../app/js"
+
+LockManager = require "#{APP_PATH}/infrastructure/LockManager"
+ProjectCreationHandler = require "#{APP_PATH}/Features/Project/ProjectCreationHandler.js"
+ProjectGetter = require "#{APP_PATH}/Features/Project/ProjectGetter.js"
+ProjectEntityMongoUpdateHandler = require "#{APP_PATH}/Features/Project/ProjectEntityMongoUpdateHandler.js"
+UserCreator = require "#{APP_PATH}/Features/User/UserCreator.js"
+
+expect = require("chai").expect
+_ = require("lodash")
+
+# These tests are neither acceptance tests nor unit tests. It's difficult to
+# test/verify that our locking is doing what we hope.
+# These tests call methods in ProjectGetter and ProjectEntityMongoUpdateHandler
+# to see that they DO NOT work when a lock has been taken.
+#
+# It is tested that these methods DO work when the lock has not been taken in
+# other acceptance tests.
+
+describe "ProjectStructureMongoLock", ->
+	describe "whilst a project lock is taken", ->
+		before (done) ->
+			# We want to instantly fail if the lock is taken
+			LockManager.MAX_LOCK_WAIT_TIME = 1
+			userDetails =
+				holdingAccount:false,
+				email: 'test@example.com'
+			UserCreator.createNewUser userDetails, (err, user) =>
+				@user = user
+				throw err if err?
+				ProjectCreationHandler.createBlankProject user._id, 'locked-project', (err, project) =>
+					throw err if err?
+					@locked_project = project
+					lockKey = ProjectEntityMongoUpdateHandler.getProjectMongoLockKey @locked_project._id
+					LockManager._getLock lockKey, done
+
+		after (done) ->
+			lockKey = ProjectEntityMongoUpdateHandler.getProjectMongoLockKey @locked_project._id
+			LockManager._releaseLock lockKey, done
+
+		describe 'interacting with the locked project', ->
+			LOCKING_UPDATE_METHODS = ['addDoc', 'addFile', 'mkdirp', 'moveEntity', 'renameEntity', 'addFolder']
+			for methodName in LOCKING_UPDATE_METHODS
+				it "cannot call ProjectEntityMongoUpdateHandler.#{methodName}", (done) ->
+					method = ProjectEntityMongoUpdateHandler[methodName]
+					args = _.times(method.length - 2, _.constant(null))
+					method @locked_project._id, args, (err) ->
+						expect(err).to.deep.equal new Error("Timeout")
+						done()
+
+			it "cannot get the project without a projection", (done) ->
+				ProjectGetter.getProject @locked_project._id, (err) ->
+					expect(err).to.deep.equal new Error("Timeout")
+					done()
+
+			it "cannot get the project if rootFolder is in the projection", (done) ->
+				ProjectGetter.getProject @locked_project._id, rootFolder: true, (err) ->
+					expect(err).to.deep.equal new Error("Timeout")
+					done()
+
+			it "can get the project if rootFolder is not in the projection", (done) ->
+				ProjectGetter.getProject @locked_project._id, _id: true, (err, project) =>
+					expect(err).to.equal(null)
+					expect(project._id).to.deep.equal(@locked_project._id)
+					done()
+
+		describe 'interacting with other projects', ->
+			before (done) ->
+				ProjectCreationHandler.createBlankProject @user._id, 'unlocked-project', (err, project) =>
+					throw err if err?
+					@unlocked_project = project
+					done()
+
+			it "can add folders to other projects", (done) ->
+				ProjectEntityMongoUpdateHandler.addFolder @unlocked_project._id, @unlocked_project.rootFolder[0]._id, 'new folder', (err, folder) ->
+					expect(err).to.equal(null)
+					expect(folder).to.be.defined
+					done()
+
+			it "can get other projects without a projection", (done) ->
+				ProjectGetter.getProject @unlocked_project._id, (err, project) =>
+					expect(err).to.equal(null)
+					expect(project._id).to.deep.equal(@unlocked_project._id)
+					done()