I’m Eric Tummers, Technical Consultant at Valid, and this is how I work

I’m hired as a Software Architect to build a solution with Microsoft products. Our team works by the scrum guide and is moving towards continuous deployment. We are learning and growing while delivering business value. This is hard work. Every sprint we complete means the retrospective is done in the pub.

I expect the best and I give the best. Here’s the beer. Here’s the entertainment. Now have fun. That’s an order!

Location: Sittard, NL
Current Gig: Technical Consultant, Valid
Word that best describes how you work: Teamwork
Current mobile device: iPhone se
Current computer: MacBook 15 inch

What apps/software/tools can’t you live without? Why?

Wunderlist: work tasks, chores, groceries, planning, every task is there.
Evernote: I’m a fan for years now. Not to happy about the recent update but time will improve this.
iSmoothrun: when I’m not working, I’m running, this app tracks just about every metric I can think of and shares it to all the platforms (runkeeper for one)
Parallels 11: Running Windows on my MacBook is a must. And of course visual studio, team foundation server, build, release manager, sql server management studio, remote desktop, powershell, and some other tools I need for work.

What’s your workspace setup like?

Work at the office is on a thin client with 21 inch screen and (wired) mouse and keyboard. The desk and chair comply with all regulations. We have a great coffee machine.


My home workspace has moved to the kitchen table with my Macbook 15 inch. No externals and enough battery for the whole day. Freedom!

What’s your best time-saving shortcut/life hack?

Timebox. Start on a task and spent the time you’ve got to get the best result. Get someone to look at it, get feedback. Then decide if the result is final or to spent some more time.

Besides your phone and computer, what gadget can’t you live without and why?

I’ve been running with my Magellan Echo for some time. It is a sports watch that hooks up to my phone by bluetooth to start / stop my runs, control the music and see the metrics right on my wrist. It is powered by a battery that lasts 6 months and is easy to replace.
My Apple TV2 (jailbroken) hooked up to my NAS for movies and series. Also hooked to my stereo for music streaming. Awesome device!

What everyday thing are you better at than everyone else? What’s your secret?

Learning new things. My current project lets me implement new things (joy) Also I try to learn the things I know to my team or anyone who listens.
I have a basic understanding of how things work and try to map new things on there. For the details I have a Pluralsight subscription and black belt google skills.

What do you listen to while you work?

My alarm clock plays classical music to wake me up in the morning. The car stereo plays about everything (grunge, rock, kids stories) driving to work. When I need some focus I play drum and bass on my headphones. My ringtone is still Run riot by Camo & Krooked.

What are you currently reading?

Tools of Titans by Tim Ferriss. A Christmas gift. Best described as a book of “How I Work” posts full with tips and tricks of the titans (experts)


How do you recharge? What do you do when you want to forget about work?

Spending quality time with my wife and daughters. Phone on silent, no screens, no work. Mostly piggyback riding and thee parties
Also sports like running, fitness, climbing and snowboarding to keep me fit and healthy.

Fill in the blank: I’d love to see _________ answer these same questions.

Iris Classon, because she had to start from zero with her career shift and is now a Microsoft MVP (Most Valuable Professional).

What’s the best advice you’ve ever received?

someecards.com - Make a shit first draft you cannot edit a blank page
I believe this is a variant on a Hemingway quote.

Is there anything else you’d like to add that might be interesting to readers?

Learn Powershell. There is so much possible with Powershell. If you can learn one thing this year pick Powershell. 

Original idea from Lifehacker.com.

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Setup Boot Camp with hyper-V support

For development I’m using Windows in a Parallels VM on my MacBook Pro. To use docker on Windows I need to enable Hyper-V.

Parallels has an option called “nested virtualisation” where the guest OS can do virtualisation. For this you’ll need a Pro subscription, which I don’t have. This means I cannot use nested virtualisation.

My only option is setting up Boot Camp and boot native into Windows. My hurdles steps are listed below.

Disk space

The first step in the Boot Camp Assistant is setting up the Boot Camp partition. I want to assign 80Gb since I’m installing Windows, Visual Studio, Docker and some other development stuff. My disk reports 105Gb of free space so that’s okay .. not ..

The assistant lets me assign max 48 Gb. What is going on? Seems that local time machine backups secretly eat into your available disk space. Luckily there is a way of removing these hidden files. The assistant now lets me create the partition of 80Gb.

Remove partition

The ISO file I downloaded from the msdn subscriptions page was incompatible and resulted in an error. Looks like only the commercial version of the ISO is supported. Now I have a corrupted Boot Camp partition. To remove these I used Disk Util as described here.

After downloading the supported ISO file and rebooting (have you tried turning it off and on again) the Boot Camp assistant did the job.


After a reboot I was presented the Windows 10 installation setup. Boot Camp installed the drivers after the first login. Another reboot and Visual Studio, Docker, … all installed without issues. Happy developer 😉

Cold boot

The next day I started my MacBook into Windows and docker crashed…
The logfile presented me with this:

Virtual machine ‘MobyLinuxVM’ could not be started because the hypervisor is not running (Virtual machine ID ~some GUID~).
The following actions may help you resolve the problem:
1) Verify that the processor of the physical computer has a supported version of hardware-assisted virtualization.
2) Verify that hardware-assisted virtualization and hardware-assisted data execution protection are enabled in the BIOS of the physical computer. (If you edit the BIOS to enable either setting, you must turn off the power to the physical computer and then turn it back on. Resetting the physical computer is not sufficient.)
3) If you have made changes to the Boot Configuration Data store, review these changes to ensure that the hypervisor is configured to launch automatically.

Google suggested to run this command to check if Hypervisor was activated/present. The answer was False.

(gcim Win32_ComputerSystem).HypervisorPresent

There seems to be a virtualisation bug that disables hyper-v on a cold boot. For now I’ll be booting into macOS and then booting into Windows. The command above will return True this way and everything works.


The option of running Windows in Parallels still interested me. By installing a trial version of Parallels Desktop I was able to start the Boot Camp Windows installation from within macOS. In the trial version all options are available, so I used the nested virtualisation option. The machine creation took some time while installing the Parallels Tools. But right after the startup (again) docker crashed.

Docker also crashed when native booted into Windows. This was resolved after uninstallation of the Parallels Tools. No Parallels for now.

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A first look at IntelliTest

Looking into Visual Studio 2017 features I found that Pex was back in the form of IntelliTest. It was actually introduced in VS2015 but I’ve never seen it. Time to give it a spin.

For this I use my Traffic Demo. The solution shows how a state pattern can be used to implement complex business rules. There are already unit tests because it is a test driven development demo. I will add extra unit tests with the IntelliTest feature.

Open the solution in Visual Studio and go to the method to IntelliTest. Then open the context menu and IntelliTest > Create IntelliTest. A dialog will ask for some naming convention.


After completion there is a generated partial class that contains code to test the method selected. Some lines of comment suggest to add an Assert. I add the Assert that confirms a property is set during the action on the state.

public void VooruitIntelliTest([PexAssumeUnderTest]Auto target)
    target.Vooruit(); // English: drive
    // TODO: add assertions to method AutoIntelliTest.VooruitIntelliTest(Auto)
    Assert.IsInstanceOfType(target.Verplaatsing, typeof(NaarVoren));

Now run the IntelliTests by going into the context menu and IntelliTest > Run IntelliTest. The result is shown in the IntelliTest Exploration Results. Open the warnings and see the Object creation warning. This is because there is no way for IntelliTest to vary between different states. Context menu on the warning and click Fix.


This will create a simple factory class that can be altered to allow variation between different states. Do this by adding parameters to the static Create method.

public static Auto Create(Verplaatsing verplaatsing, string bestuurder)
    Auto auto = new Auto // English: car
        Verplaatsing = verplaatsing, // English: direction
        Bestuurder = bestuurder // English: driver
    return auto;

Now run the IntelliTests again. This time some exceptions are reported.
The first is the NullReferenceException, caused by passing null for the first parameter to the Create method above. We need to tell IntelliTest to not pass null. For this the PexAssumeNotNull attribute is available which I add to the first parameter.

public static Auto Create(
     [PexAssumeNotNull]Verplaatsing verplaatsing,
     string bestuurder)
    // rest of factory method

The other exception is a exception thrown by my code because a businessrule is violated. In English the businessrule is: in case the car is driving backwards and you put it in drive an accident (ongeluk) is thrown. Again with an attribute this can be told to IntelliTest: PexAllowedExceptionFromType.

[PexAllowedExceptionFromType(typeof(Ongeluk), typeof(NaarAchteren))]
public void VooruitIntelliTest([PexAssumeUnderTest]Auto target)
    // rest of intellitest

This adds the ExpectedException attribute on the generated unit test in case the exception of type Ongeluk is thrown from the type NaarAchteren (English: Reverse) You can see this in the generated g.cs file.

// part of AutoIntelliTest.VooruitIntelliTest.g.cs
public void VooruitIntelliTestThrowsOngeluk41()
    Auto auto;
    NaarAchteren s0 = new NaarAchteren();
    auto = AutoFactory.Create((Verplaatsing)s0, (string)null);

Now compile the intellitest project and run the tests from Test Explorer with code coverage enabled. Code coverage is 100%. Good job!


Code available on github.

Final thoughts

I prefer test driven development and create the unit test first. This method of generating unit tests feels like cheating. On the other hand it creates some extra tests to up the code coverage and discovery of edge cases. Use it wise grasshopper.

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Internet services that have a great free option

Image courtesy of ratch0013 / FreeDigitalPhotos.net

The internet has a lot of services. Most of them have a free or try-for-a-period option. After trying a service I decide about the paid options stay on the free tier or discard it. Below is a list of services I use with the free tier. Some are already featured in my Dev Tool List.

Image courtesy of ratch0013 / FreeDigitalPhotos.net

  • bit.ly, shorten urls and customised urls for better sharing on slides all with stats.
  • Dropbox, the file sync platform, use it primarily for sharing documents between devices.
  • Freshdesk, self service and ticketing system for small projects.
  • Github, personal projects, demo projects, all public. Private stuff is for work.
  • Namecheap, the freedns service is free and provides the dns for my domain.
  • Opendns, monitor the internet usage for my home network.
  • Pocket, save links for later viewing on my iPad or in my browser.
  • Rescuetime, log the time I use my computer for optimisation of screen time, am I being productive?
  • Spotify, listen to new music with occasional adds.
  • Uptimerobot, 3rd party logging of website availability, keep azure free tier websites loaded by sending requests 😉
  • Wunderlist, my shopping list, my work todo, my maintenance jobs, my chores, all there.

These are the services I use. Am I missing out on something great? Let met know in the comments.

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Services I pay for and why

The internet has a lot of services. Most of them have a free or try-for-a-period option. After trying a service I decide about the paid options, stay on the free tier or discard it. Below is a list of services I pay for and why I think they are worth the money.

Evernote Premium

evernoteWith Evernote I have all my information in one place and am able to find what I need. The app is cross platform and I use it on my laptop (Win/Mac), iPhone and iPad. I’m have a premium subscription because I use the annotation and presentation features.
Alternative: Evernote free



icon_hero_icloud_largeWe use iCloud storage for pictures, mail and device backups. It integrates seamless with Photos on MacOS and iOS. I’m stil backing up the original pictures on my NAS just in case.
Alternative: 5Gb storage free with iDevice registration


iTunes Match

apple-itunes-match-and-icloud-logo-1107Yes, I’m stil using iTunes Match. The price of Apple Music (that has the same features) is so much higher that we’ll not be moving until Apple discontinues iTunes Match.
We have invested in the Apple ecosystem and play music from Apple TV, MacBook (2x), iPad (2x) and iPhone.
Alternative: iTunes server on NAS


Wired Magazine digital

wiredThe digital edition has extra media content since it has an internet connection and the printed magazine has not 😉 Got to love the “angry nerd”.


GoDaddy .NL domain

godaddy-schema-logo-minEveryone should have their own domain. I have it set up to forward requests to other locations through a free dns service. This way I can give out my own domain in slides and know people end up here.


WordPress Personal

wordpress-logoEver noticed there are no adds here? You’re welcome.
This also includes the custom .com domain and extra storage.



pluralsight-logo-vrt-color-2To be honest: my boss pays for this subscription. With Pluralsight I’m able to get up to speed really quick. I have the app on my iPad and iPhone but I mostly use it on my laptop.
TIP: signup here and we both get a discount.


These are the services I use. Am I missing out on something great? Let met know in the comments.
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My 2018 developer and power user tools

toolbox by vectorolie / FreeDigitalPhotos.net
Below a list of tools I use today. If you’re like me, you check them out and add the ones you like to your own toolbox.

Image courtesy of vectorolie / FreeDigitalPhotos.net


Chocolatey, installation automation. I’ve written about it before on my blog. (See posts)
F.lux, it makes the color of your computer’s display adapt to the time of day, on mac this is build into the OS
7-zip, the new standard in compressing files
DropBox, file share/sync between computers and the internet
Chrome, best browser today
AdBlock for Chrome, blocks adds in chrome


Powershell, the automation solution from microsoft
RescueTime, background logging of where you spend your time
Wunderlist, task list on every platform
Wunderlist parser, convert a plain list of items into wunderlist items
IFTTT, automate the internet
Trello, collaboration tool that uses boards and cards. I’ve written some small automation scripts for my uses. (Post)
Pocket, my preferred read later list, available on all platforms
Evernote, remember everything. I use it for my GTD technique called The secret weapon.
1Password, my password is CTRL + \
Autohotkey, run macro’s on keyboard shortcuts like CTRL+ALT+5 types €


Visual Studio 2017, the best IDE out there
NuGet, source of all the good in the world
Visual Studio Gallery, extend visual studio
Ghostdoc, CTRL+SHIFT+D to comment your code, that simple
Specflow, cucumber for .net for behavior driven development (BDD)
Just Decompile, see the code of .net assemblies
Fiddler, log http calls via this proxy
Wireshark, deep logging of network traffice
SourceTree, my preferred git tool with advanced branching support
Notepad++, notepad on steroids
BrowserStack, test webpages on any platform, live or automated
Selenium, webbrowser automation, also runs on browserstack
Sqlite studio, manage Sqlite files
Azure Storage Explorer, browse and manage Azure Storage
Snoop WPF, spy on WPF
Pester, test and mock framework for PowerShell.


ZoomIt, I use this in all my demos to zoom
Bit.ly, url shortener service
windirstat, see what is hogging your hard disk space
prey, install and forget, until you need it
Gifcam, screen recorder with animated gif support
Notebook fancontrol, see processor temperature and set the fan speed


Cyberduck, connect to anything
DaisyDisk, see what is hogging your hard disk space
Type2phone, make my mac a Bluetooth keyboard for iPad or AppleTV
Handbrake, convert movies
1Password, my password is ⌘ + \
Little snitch, monitor network traffic coming from your mac
HyperDock, preview windows from the dock
Alfred, spotlight replacement with lots of options
Parallels, the virtualisation solution for mac
Sublime Text, very complete text editor for code
Visual Studio Code, code editor for any platform
Gimp, freeware photo editor with all the bells and whistles you’ll need


Tweetbot, easy twitter client with pocket integration
Workflow, automate tasks, like send ETA and navigate home
Spark, handles my e-mail and offers tasks like send to evernote or pocket
Pocket, I do my reading mostly on iPhone or iPad
Duet, use your iPad as an extra screen
Lightningtalktimer, timer app that changes appearance with time passed

Some of the tools cost money, some are free, some offer paid options. If it saves you time or improves your work, why not support the developer that made it possible?


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VS2017 Live unit testing in Parallels Desktop VM

TLDR; change the project location on disk from shared mac (my documents) to local windows (c:-drive) to prevent Live unittesting from crashing

Live unit testing has been introduced in 2016 (visual studio blog) and got my attention recently by a tweet from Iris Classon. 

Since I’m on a Mac my way of working with Visual Studio is with virtualisation. I have Windows 10 running in Parallels Desktop and installed Visual Studio 2017 enterprise. The enterprise version contains the live unit testing feature. If you don’t see it check the version of VS2017 you’re running.

After creating a simple solution with some unit tests I started the live unit testing feature. This can be done in the menu Test > Live unit testing > Start. The output window showed it was compiling and then the thing crashed … Microsoft.CodeAnalysis.LiveUnitTesting has stopped working …

I’ve noticed strange behaviour before when the projects are located in the my documents folder. This is the default location for visual studio projects. In Parallels this location is mapped to the documents folder of the Mac user on the host machine. Windows 10 sees this as a network / mapped drive location and does not trust it by default.

I moved the solution to the local c:-drive and got live unit testing to work without problems. Loving it already. Got to agree with Iris about this one.

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Microsoft Fakes misbehave on buildserver

We use Microsoft Fakes to isolate some legacy code. Today I added some tests that passed on my machine, but failed on the buildserver. 😦

After reading this stackoverflow post I added the

using(ShimsContext.Create()) {
   var fakeObject = new some.namespace.Fakes.LegacyObject();
   // ... rest of test

and the builds became green again 😉

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