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Asked: 2026-05-11T12:05:02+00:00

I currently have a method within my class that has to call other methods,

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I currently have a method within my class that has to call other methods, some in the same object and others from other objects. 

  class MyClass {     public function myMethod()     {         $var1 = $this->otherMethod1();         $var2 = $this->otherMethod2();         $var3 = $this->otherMethod3();         $otherObject = new OtherClass();         $var4 = $otherObject->someMethod();          # some processing goes on with these 4 variables         # then the method returns something else          return $var5;     } }

I’m new to the whole TDD game, but some of what I think I understood to be key premises to more testable code are composition, loose coupling, with some strategy for Dependency Injection/Inversion of Control.

How do I go about refactoring a method into something more testable in this particular situation?

Do I pass the $this object reference to the method as a parameter, so that I can easily mock/stub the collaborating methods? Is this recommended or is it going overboard? 

  class MyClass {     public function myMethod($self, $other)     {         # $self == $this         $var1 = $self->otherMethod1();         $var2 = $self->otherMethod2();         $var3 = $self->otherMethod3();         $var4 = $other->someMethod();          # ...          return $var5;     } }

Also, it is obvious to me that dependencies are a pretty big deal with TDD, as one has to think about how to inject a stub/mock to the said method for tests. Do most TDDers use DI/IoC as a primary strategy for public dependencies? at which point does it become exaggerated? can you give some pointers to do this efficiently?

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1 Answer

  1. These are some good questions… let me first say that I do not really know JS at all, but I am a unit tester and have dealt with these issues. I first want to point out that JsUnit exists if you are not using it.

    I wouldn’t worry too much about your method calling other methods within the same class… this is bound to happen. What worries me more is the creation of the other object, depending on how complicated it is.

    For example, if you are instantiating a class that does all kinds of operations over the network, that is too heavy for a simple unit test. What you would prefer to do is mock out the dependency on that class so that you can have the object produce the result you would expect to receive from its operations on the network, without incurring the overhead of going on the network: network failures, time, etc…

    Passing in the other object is a bit messy. What people typically do is have a factory method to instantiate the other object. The factory method can decide, based on whether or not you are testing (typically via a flag) whether or not to instantiate the real object or the mock. In fact, you may want to make the other object a member of you class, and within the constructor, call the factory, or make the decision right there whether or not to instantiate the mock or the real thing. Within the setup function or within your test cases you can set special conditions on the mock object so that it will return the proper value.

    Also, just make sure you have tests for your other functions in the same class… I hope this helps!

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