Net Objectives

APRIL 5, 2019

TDD, when conducted as a specifying activity, is an aspect of Behavior-Driven Development (BDD). Therefore, when structuring the tests in TDD we can be guided by the language of BDD: Given, When, Then. Given the system is in a known … Continue reading "TDD and Test Anatomy".

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APRIL 3, 2019

When first adopting TDD, developers can run into some roadblocks that seem to indicate that TDD is a difficult process. For example, developers will struggle to write unit tests of behavior that is embedded in a user interface, or in stored procedures … Continue reading "TDD and System Architecture".

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MARCH 11, 2019

TDD views this very differently. In TDD, a “defect” is code that … Continue reading "TDD and Reported Defects". Typically, a “trouble ticket” or similar artifact is generated, and someone is assigned the task to 1) locate and then 2) fix the errant code.

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MAY 20, 2019

Ideally in TDD, no more than one test is ever failing at any given point in time. We want the suite to get back to “all green” as quickly … Continue reading "TDD: Keeping Tests Green". This test represents the work that is about to be done but hasn’t yet. Also, this test should not spend a long time in the red.

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MAY 16, 2019

TDD is a powerful way to develop new code. In his excellent book, Working Effectively with Legacy Code, Michael Feathers outlines techniques … Continue reading "TDD and Legacy Code". In his excellent book, Working Effectively with Legacy Code, Michael Feathers outlines techniques … Continue reading "TDD and Legacy Code".

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MAY 7, 2019

TDD depends on a strong connection between the automation of the test suite and the system itself. So, if errors creep into the test … Continue reading "Sustainable TDD: Part 3". So, if errors creep into the test … Continue reading "Sustainable TDD: Part 3". The problem is automated tests pass by default.

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MARCH 20, 2019

Because TDD is “test” driven development, people tend to think of TDD as “writing tests first.” In fact, TDD is not a testing activity per se. Because of this … Continue reading "Commonly Missing Tests in TDD". Because of this … Continue reading "Commonly Missing Tests in TDD".

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MAY 3, 2019

So, when the team adopts TDD, it is understandable that attention is paid to the level of resource needed to sustain it over time. It’s not uncommon for project managers to notice, as the project grows, that the … Continue reading "Sustainable TDD: Part 2". Spending them on one thing means not spending them on another.

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TDD Sustainability Project Management Resources 40

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APRIL 17, 2019

In TDD, tests take actions such as Setup, Trigger, and Verify. For example, If … Continue reading "TDD and Guard Assertions". Each of these pieces must successfully execute in order for the specification to be verified as accurate to the current behavior of the system.

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APRIL 26, 2019

In TDD and Code Coverage, we established that code coverage tools do not provide useful project metrics, in and of themselves. In TDD, we don’t use code coverage tools for this purpose because we don’t need to. Continue reading "TDD and Code Coverage Tools".

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MARCH 21, 2019

TDD is different from QA in many respects. The government will dictate how quickly a … Continue reading "Specifying Constants in TDD". The government will dictate how quickly a … Continue reading "Specifying Constants in TDD". Part of this involves the tests we choose to write.

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MARCH 19, 2019

Similarly, TDD was first promoted around the same time in history as part of eXtreme Programming. Some have suggested that these two points of view stand in opposition to each other, saying Design patterns are about up-front design, while … Continue reading "TDD and Design Patterns".

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MARCH 8, 2019

Since TDD focuses on driving new behavior from tests, how would refactoring play … Continue reading "Refactoring Applied to TDD". It is usually thought of as a way to deal with old legacy code that is functional but poorly designed and thus hard to work with.

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APRIL 29, 2019

This is my 48th post in this series on TDD. I wanted to bring some of this material together and engage with the notion of TDD as a sustainable process. There are those … Continue reading "TDD as a Sustainable Process: Introduction".

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APRIL 10, 2019

TDD is not really a testing activity so much as it is about the creation of an executable specification. Many IDE’s will … Continue reading "TDD and Naming: Part 1". Because of this we value different things than testers might. Naming of tests, variables, and the use of well-named customized assertions are examples.

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APRIL 22, 2019

Part of the TDD process consists of writing failing tests before the code that will eventually make them pass. Test-first alone is not TDD per se, but it is a part of it. This comes from the fact that these tests have the … Continue reading "TDD: Tests are Client Number 1".

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MAY 31, 2019

I have just posted the sixtieth entry in this series and this seemed like enough content to gather into a sort … Continue reading "Announcing the TDD Companion". Many people have commented positively on this work.

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MAY 9, 2019

But if all behavior in TDD needs to be tested, and if instance behavior implemented in abstract classes cannot be tested … Continue reading "TDD: Testing Adapters for Abstract Classes".

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TDD Testing 40

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MAY 28, 2019

As our industry matures it becomes increasingly true that we don’t need to re-invent the wheel For example, if code is written that is required to send data over a TCP-IP connection in, say, C#, the tendency is for … Continue reading "TDD and Inflection Points".

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APRIL 19, 2019

No attempt will be made here to engage in this debate, but it is interesting to note the role of TDD in languages that are not … Continue reading "TDD and Dynamically-Typed/Interpreted Languages".

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MARCH 26, 2019

Recently I wrote about the necessity in TDD of specifying both sides of a behavioral boundary, and its epsilon. It has to do with the … Continue reading "Specifying Boundaries in TDD: Part 2". This is important because we want a complete, detailed record of the critical business rules and other values in the system.

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MARCH 25, 2019

We call this kind of behavioral change a “boundary” and it should be specified as such in TDD. For example, let’s say there is a business rule that dictates how a passed-in value should be … Continue reading "Specifying Boundaries in TDD: Part 1".

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MARCH 29, 2019

When an exception is declared in … Continue reading "Specifying Exceptions in TDD". They are used when there is a potential problem that cannot be detected by the compiler, linker, or other automated aspect of the development process, and thus may potentially make it into the released product.

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MARCH 7, 2019

Some organizations who have adopted TDD as their development strategy have assumed that they no longer need SAT/QA testers, since the developers are now writing tests. Developers write the tests they need to drive correct behavior into the … Continue reading "TDD does not Replace Traditional Testing". This is a mistake.

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FEBRUARY 25, 2019

I mentioned earlier that TDD offers qualitative measurements about production code, namely that a large average fixture size can be used to measure relative coupling in a system. The Single Responsibility Principle states that every class in … Continue reading "TDD and the Single Responsibility Principle".

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MARCH 12, 2019

Often the developers understand and agree that these qualities are important, but they are not … Continue reading "“Good” Tests in TDD". Is it cohesive, decoupled, non-redundant, encapsulated, open-closed, and so forth?

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MARCH 1, 2019

This means that a “good” design will allow for a new behavior to be added to a system without having to change the existing code, or at least to minimize … Continue reading "TDD and the OCP".

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FEBRUARY 15, 2019

Measurement tools are used as a process gate, where the team must achieve this minimum coverage level before code can be checked … Continue reading "TDD and Code Coverage". This is usually expressed as a percentage: at least X% of all code developed must be covered by tests.

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APRIL 15, 2019

Unit testing frameworks, which are the most common tools used by developers to conduct TDD, come with pre-made assertions that can be used to verify the behaviors being specified. The creation of … Continue reading "TDD and Naming Part 3: Customized Assertions".

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MAY 31, 2019

The implication would be that the object has … Continue reading "Specifying the Negative in TDD". For example, we might test-drive a value object that represents some domain information, and the requirement for it might include that the object must be “immutable.”

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MAY 31, 2019

If you push Button B, you will have 80% code … Continue reading "TDD and the Magic Buttons". Imagine there are two magic buttons in front of you. You know, without any doubt that if you press Button A then your code will suddenly have 90% code coverage.

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MAY 21, 2019

The level of precision required … Continue reading "TDD and Accuracy vs. Precision". One can be: Accurate, but not precise: “Pi is a little over three.” Precise, but not accurate: “Pi is 5.393858303895.” They are not the same but they are related.

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MARCH 28, 2019

Specifying a workflow in #TDD means writing a test that says, “When entity A is called upon to accomplish a task, it must interact with entity B is the following way.” Continue reading "Specifying Workflows in TDD, Part 2: How".

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MARCH 27, 2019

This is as true in TDD as it is in traditional testing. Most workflows are implementation … Continue reading "Specifying Workflows in TDD, Part 1: Why". Often these interactions themselves are not exposed outside the system, and so only their resulting behavior should be tested.

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APRIL 11, 2019

For example, if we had a system behavior that converted a temperature expressed in Fahrenheit to one expressed in Celsius, then the test that specified this might have an assertion along these lines: assertEquals(100, … Continue reading "TDD and Naming: Part 2".

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FEBRUARY 14, 2019

TDD tells us what we do not know. Imagine you are developing the software for a casino’s poker slot machine … Continue reading "TDD Tells Us What is not Known". You cannot meaningfully test that which you do not adequately understand. The time to find that out is before you start development.

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MARCH 5, 2019

This is one area where … Continue reading "TDD and the Separation of Concerns". This adds clarity, promotes re-use, improves cohesion, and in general adds value to the work. It can be difficult to know, however, if one has separated things sufficiently, or perhaps has overdone it.

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