diff --git a/.env.example b/.env.example
index 545d8e5..c80e4b5 100644
--- a/.env.example
+++ b/.env.example
@@ -1,2 +1,2 @@
 # connection string for mongodb in the form of "mongodb://user:password@host:port/db"
-MONGO_CONN_STR=mongodb://timo:bert@127.0.0.1:27017/timobert
+MONGO_CONN_STR=mongodb://timo:bert@127.0.0.1:27017/testSuite
diff --git a/.mocharc.js b/.mocharc.js
index 16f1c79..90803de 100644
--- a/.mocharc.js
+++ b/.mocharc.js
@@ -1,5 +1,6 @@
 import { readFileSync } from "fs";
 
-const envFile = readFileSync('./.env', { encoding: 'utf8' });
-
-process.env.MONGO_CONN_STR = envFile.split('MONGO_CONN_STR=')[1].split('\n')[0];
\ No newline at end of file
+try {
+  const envFile = readFileSync('./.env', { encoding: 'utf8' });
+  process.env.MONGO_TEST_CONN_STR = envFile.split('MONGO_TEST_CONN_STR=')[1].split('\n')[0];
+} catch (e) {}
diff --git a/lib/db.js b/lib/db.js
index 930e31f..6a86375 100644
--- a/lib/db.js
+++ b/lib/db.js
@@ -1,30 +1,50 @@
 import { MongoClient } from 'mongodb';
-/*
-console.log('connecting to ' + process.env.MONGO_CONN_STR);
-const 
-*/
+
 let mongo;
 let db;
 let functionCollection = {};
 
 export function init(connectionString) {
-  console.log(connectionString);
-  mongo = new MongoClient(connectionString);
-  mongo.connect().catch(e => {throw e});
-  db = mongo.db();
-
-  return functionCollection;
+  try {
+    mongo = new MongoClient(connectionString);
+    db = mongo.db();
+    return mongo.connect().then(() => Promise.resolve(functionCollection));
+  } catch (e) {
+    return Promise.reject(e);
+  }
 }
 
-functionCollection.subsribe = function subsribe (b) {
-  let collection = db.collection(b);
-  collection.find({}, {}).toArray().then(r => console.log);
+functionCollection.subscribe = function subscribe (collectionName, filter) {
+  let collection = db.collection(collectionName);
+  return collection
+    .find(filter, {})
+    .toArray();
 }
 
-functionCollection.persist = function persist (b) {
-  console.log('persist');
+functionCollection.persist = function persist (collectionName, filter, fieldName, value) {
+  let collection = db.collection(collectionName);
+  let newValue = { $set: {} };
+  newValue.$set[fieldName + ".modifiedAt"] = Date.now();
+  newValue.$set[fieldName + ".modifiedBy"] = "anonymous";
+  newValue.$set[fieldName + ".transientValue"] = value;
+
+  return collection.updateMany(filter, newValue, { upsert: true });
 }
 
 functionCollection.publish = function publish (b) {
   console.log('publish')
+}
+
+functionCollection.close = function close () {
+  return mongo.close();
+}
+
+functionCollection.purge = function purge (collectionNames) {
+  let promises = [];
+
+  for (let i = 0; i < collectionNames.length; i++) {
+    const collection = db.collection(collectionNames[i]);
+    promises.push(collection.drop());
+  }
+  return Promise.all(promises);
 }
\ No newline at end of file
diff --git a/package.json b/package.json
index 8744188..56f6776 100644
--- a/package.json
+++ b/package.json
@@ -5,6 +5,7 @@
   "type": "module",
   "scripts": {
     "test": "mocha",
+    "testWatch": "mocha -w",
     "start": "node --env-file=.env index.js",
     "watch": "node --watch --env-file=.env index.js"
   },
diff --git a/test/db.test.js b/test/db.test.js
index aeed9f9..27bd3c4 100644
--- a/test/db.test.js
+++ b/test/db.test.js
@@ -1,12 +1,53 @@
-import mocha from 'mocha';
-import { subscribe } from '../lib/db.js';
+import { before } from 'mocha';
+import * as db from '../lib/db.js';
+import * as assert from 'assert/strict';
 
-const assert = mocha.assert;
+const rng = Math.random();
 
 describe('lib/db', function () {
-  describe('#indexOf()', function () {
-    it('should return -1 when the value is not present', function () {
-      assert.equal([1, 2, 3].indexOf(4), -1);
+  let myDb;
+  let dbFuncs;
+  
+  describe('#init()', function () {
+    it('should fail to connect given invalid connection string', function () {
+      return db.init('not a connection string').then(() => Promise.reject()).catch(() => Promise.resolve());
+    });
+    it('should successfully connect to mongodb', function () {
+      return myDb = db.init(process.env.MONGO_TEST_CONN_STR);
+    });
+  });
+  describe('#close()', function () {
+    it('should close the connection', function () {
+      return myDb.then(db => db.close());
+    });
+  });
+
+  describe('with a established connection ->', function () {
+    before(function () {
+      myDb = db.init(process.env.MONGO_TEST_CONN_STR)
+        .then(funcs => dbFuncs = funcs);
+    });
+
+    after(function () {
+      dbFuncs.purge(['readWriteTest'])
+        .then(() => myDb.then(db => db.close()));
+    });
+
+    describe('#persist()', function () {
+      it('should be able to write to mongodb', function () {
+        return dbFuncs.persist('readWriteTest', {}, 'rng', rng);
+      });
+    });
+
+    describe('#subscribe()', function () {
+      it('should be able to read from mongodb', function () {
+        return dbFuncs
+          .subscribe('readWriteTest', {})
+          .then(v => {
+            assert.equal(v.length, 1);
+            assert.equal(v[0].rng.transientValue, rng);
+          });
+      });
     });
   });
 });
\ No newline at end of file