Dennis Doomen
@dennisdoomen.com
Microsoft MVP | Coding Architect | .NET Tech Lead | .NET & C# | TypeScript | Fluent Assertions Author | International Speaker | Occasional Trainer | React & VueJS | Event Sourcing Veteran | DDD Designer | TDD Practitioner | Clean Code Writer
Mockly, my new .NET HTTP mocking library has its own website now. Check it out at mockly.org
February 16, 2026 at 3:29 PM
Mockly, my new .NET HTTP mocking library has its own website now. Check it out at mockly.org
Chuck Norris: The Chosen One
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February 16, 2026 at 10:17 AM
The number of times I'm having @jetbrains.com #Junie do two things concurrently on two solutions open in two instances of #Rider is increasing by the day. In fact, I'm doing it while I'm typing this...
a cat is sitting in front of a laptop with the words busy busy busy below it .
ALT: a cat is sitting in front of a laptop with the words busy busy busy below it .
media.tenor.com
February 13, 2026 at 5:22 PM
The number of times I'm having @jetbrains.com #Junie do two things concurrently on two solutions open in two instances of #Rider is increasing by the day. In fact, I'm doing it while I'm typing this...
February 12, 2026 at 2:57 PM
Although version 8.9 of #fluentassertions is on the way, we couldn't help ourselves and also ship a tiny bugfix for version 7. See github.com/fluentassert...
February 10, 2026 at 1:08 PM
Although version 8.9 of #fluentassertions is on the way, we couldn't help ourselves and also ship a tiny bugfix for version 7. See github.com/fluentassert...
Oh dear. GitHub is down...
February 9, 2026 at 4:36 PM
Oh dear. GitHub is down...
Last night, I've released version 1.2 of Mockly. It improves the failure message that it produces if the actual HTTP request did not match any of the mocked calls. It also includes information about the actual request body. Check out the release notes at github.com/dennisdoomen...
February 9, 2026 at 1:45 PM
Last night, I've released version 1.2 of Mockly. It improves the failure message that it produces if the actual HTTP request did not match any of the mocked calls. It also includes information about the actual request body. Check out the release notes at github.com/dennisdoomen...
I've shipped a new version of Reflectify, a .NET library full of convenient extension methods to make working with Reflection a lot easier. And what's even cooler, this package comes as a source-only NuGet package. If you use it, you don't get a binary dependency on another DLL.
February 3, 2026 at 4:06 PM
I've shipped a new version of Reflectify, a .NET library full of convenient extension methods to make working with Reflection a lot easier. And what's even cooler, this package comes as a source-only NuGet package. If you use it, you don't get a binary dependency on another DLL.
Another quality-of-life feature in Fluent Assertions 8 is the way a construct like...
action.Should().Throw<SomeException>().WithMessage("*some wildcard*")
...reports the difference between the actual exception message and the expected one.
action.Should().Throw<SomeException>().WithMessage("*some wildcard*")
...reports the difference between the actual exception message and the expected one.
January 28, 2026 at 4:33 PM
Another quality-of-life feature in Fluent Assertions 8 is the way a construct like...
action.Should().Throw<SomeException>().WithMessage("*some wildcard*")
...reports the difference between the actual exception message and the expected one.
action.Should().Throw<SomeException>().WithMessage("*some wildcard*")
...reports the difference between the actual exception message and the expected one.
Because of the negative reviews I was hesitant about "Avatar: Fire and Ash". But because of a lazy Sunday, I took my son to our local IMAX 3D HFR cinema after all. I'm so happy I did. I loved the visuals, I was genuinely moved by the story, and I was blown away by the music. Go see it!
January 26, 2026 at 1:28 PM
Because of the negative reviews I was hesitant about "Avatar: Fire and Ash". But because of a lazy Sunday, I took my son to our local IMAX 3D HFR cinema after all. I'm so happy I did. I loved the visuals, I was genuinely moved by the story, and I was blown away by the music. Go see it!
One of the small quality-of-life features in Fluent Assertions 8 is that it will provide more context when two strings differ in a construct like "subject.Should().Be(expected)".
Note that "BeEquivalentTo" will only do that when the IncludingFullStringsInDifference option is used.
Note that "BeEquivalentTo" will only do that when the IncludingFullStringsInDifference option is used.
January 26, 2026 at 12:45 PM
One of the small quality-of-life features in Fluent Assertions 8 is that it will provide more context when two strings differ in a construct like "subject.Should().Be(expected)".
Note that "BeEquivalentTo" will only do that when the IncludingFullStringsInDifference option is used.
Note that "BeEquivalentTo" will only do that when the IncludingFullStringsInDifference option is used.
Soon, at a conference or event near you...
January 21, 2026 at 3:53 PM
Soon, at a conference or event near you...
Although #Mockly's fluent API provides a lot of power to build complicated HTTP mocks, sometimes you just want to provide a full URL with wildcards. Well, that's supported too.
Check out the documentation at github.com/dennisdoomen...
Check out the documentation at github.com/dennisdoomen...
January 20, 2026 at 12:20 PM
Although #Mockly's fluent API provides a lot of power to build complicated HTTP mocks, sometimes you just want to provide a full URL with wildcards. Well, that's supported too.
Check out the documentation at github.com/dennisdoomen...
Check out the documentation at github.com/dennisdoomen...
One of the most annoying aspects of a lot of HTTP mocking libraries in .NET is that it takes way too much time to figure out why the mock wasn't invoked correctly. E.g. Did I use the wrong path? The wrong query maybe? Did I make a mistake in the order? Especially with the more complicated...
January 12, 2026 at 7:27 PM
One of the most annoying aspects of a lot of HTTP mocking libraries in .NET is that it takes way too much time to figure out why the mock wasn't invoked correctly. E.g. Did I use the wrong path? The wrong query maybe? Did I make a mistake in the order? Especially with the more complicated...
Looking forward to what 2026 will bring for me in terms of conferences. But I can already confirm you will find me in Redmond, Stockholm, Athens, Krakow and Mannheim.
January 7, 2026 at 7:35 AM
Looking forward to what 2026 will bring for me in terms of conferences. But I can already confirm you will find me in Redmond, Stockholm, Athens, Krakow and Mannheim.
I know it's cheesy at best, but I couldn't resist myself. So this is what 2025 looked like for me.
⏬ 150 million downloads of my projects
💰1 open-source project got commercial
⭐4 new open-source projects with 24K downloads in total...
⏬ 150 million downloads of my projects
💰1 open-source project got commercial
⭐4 new open-source projects with 24K downloads in total...
January 5, 2026 at 3:30 PM
I know it's cheesy at best, but I couldn't resist myself. So this is what 2025 looked like for me.
⏬ 150 million downloads of my projects
💰1 open-source project got commercial
⭐4 new open-source projects with 24K downloads in total...
⏬ 150 million downloads of my projects
💰1 open-source project got commercial
⭐4 new open-source projects with 24K downloads in total...
I don't know why, but somehow 2025 has been the year were I suddenly felt energized to create a whole bunch of new open-source projects. In fact, I started 5 (!) new projects in the last 15 months, next to continuing the development of FluentAssertions (and we're at 8.8 now). (cont'd)
December 30, 2025 at 3:19 PM
I don't know why, but somehow 2025 has been the year were I suddenly felt energized to create a whole bunch of new open-source projects. In fact, I started 5 (!) new projects in the last 15 months, next to continuing the development of FluentAssertions (and we're at 8.8 now). (cont'd)
I've released Mockly 1.1:
🔧Add RespondsWith overloads for HttpContent instances
🔧Add IResponseBuilder interface for test data builder integration
🔧Fixed a bug where a custom port number wasn't always honored
🔧Throwing an exception from RespondsWith is tracked as a request
🔧Add RespondsWith overloads for HttpContent instances
🔧Add IResponseBuilder interface for test data builder integration
🔧Fixed a bug where a custom port number wasn't always honored
🔧Throwing an exception from RespondsWith is tracked as a request
December 24, 2025 at 6:20 AM
I've released Mockly 1.1:
🔧Add RespondsWith overloads for HttpContent instances
🔧Add IResponseBuilder interface for test data builder integration
🔧Fixed a bug where a custom port number wasn't always honored
🔧Throwing an exception from RespondsWith is tracked as a request
🔧Add RespondsWith overloads for HttpContent instances
🔧Add IResponseBuilder interface for test data builder integration
🔧Fixed a bug where a custom port number wasn't always honored
🔧Throwing an exception from RespondsWith is tracked as a request
Are you struggling to build well-designed (open-source or closed source) libraries that are distributed over NuGet.org or Azure DevOps Artifacts, then check out my .NET Library Starter Kit.
It contains everything I've learned from maintaining libraries with millions of downloads.
It contains everything I've learned from maintaining libraries with millions of downloads.
December 17, 2025 at 6:24 AM
Are you struggling to build well-designed (open-source or closed source) libraries that are distributed over NuGet.org or Azure DevOps Artifacts, then check out my .NET Library Starter Kit.
It contains everything I've learned from maintaining libraries with millions of downloads.
It contains everything I've learned from maintaining libraries with millions of downloads.
600 million downloads.... That's what happened during the weekend...
And yes, v7 is still fully open-source, free and fully supported with important bug fixes. And if you need all the power of v8, it's only $14.95 per year per developer.
And yes, v7 is still fully open-source, free and fully supported with important bug fixes. And if you need all the power of v8, it's only $14.95 per year per developer.
December 15, 2025 at 5:24 PM
600 million downloads.... That's what happened during the weekend...
And yes, v7 is still fully open-source, free and fully supported with important bug fixes. And if you need all the power of v8, it's only $14.95 per year per developer.
And yes, v7 is still fully open-source, free and fully supported with important bug fixes. And if you need all the power of v8, it's only $14.95 per year per developer.
Are C# developers still using the "event" keyword anymore? I haven't used it in a decade or so.
December 12, 2025 at 4:50 PM
Are C# developers still using the "event" keyword anymore? I haven't used it in a decade or so.
When an unexpected request occurs and there are multiple configured HTTP mocks, Mockly helps you diagnose that by reporting the closest matching mock (method, scheme/host/path/query) so you can quickly see what to adjust in your setup. Check out Mockly at github.com/dennisdoomen...
December 9, 2025 at 6:36 PM
When an unexpected request occurs and there are multiple configured HTTP mocks, Mockly helps you diagnose that by reporting the closest matching mock (method, scheme/host/path/query) so you can quickly see what to adjust in your setup. Check out Mockly at github.com/dennisdoomen...
The last couple of weeks, I've been working on a new open-source project called #Mockly, a mocking library for the .NET HttpClient. It provides a fluent API for configuring HTTP request mocks, capturing request details, and asserting on HTTP (cont'd)
December 8, 2025 at 2:31 PM
The last couple of weeks, I've been working on a new open-source project called #Mockly, a mocking library for the .NET HttpClient. It provides a fluent API for configuring HTTP request mocks, capturing request details, and asserting on HTTP (cont'd)
I'm starting this week with a big smile. Not only because I had a great weekend, but mostly because I genuinely enjoyed being at the #DDC2025 conference in #Cologne. It's the perfect conference to wrap up a long year of conference talks. Why is that? Because it's organized by...
December 1, 2025 at 4:58 PM