Skip to main content

Mockito


fowarded from http://monkeyisland.pl/2008/01/14/mockito/

Mockito

I’m a mockist but existing mock frameworks just don’t appeal to me. They spoil my TDD experience. They harm code readability. I needed something better. That’s why I came up with Mockito.

Syntax

Here is a what I think about mocking syntax:
  • Let’s keep it simple: interactions are method calls. There is no point in building sophisticated mocking language for method calls in Java. There is already a language for that. It’s called Java.
  • The less DSL the better. Interactions are just method calls. Method calls are simple, DSL is complex.
  • No Strings for methods. I spent more time reading code than writing it. Therefore I want the code to be readable. String literals pretending to be methods cannot compete with actual method calls. Even IDEs decorate literals differently so my mind will always adopt the real method call quicker than any literal trying to impersonate a method.
  • No anonymous inner classes. They bring more indentation, more curly brackets, more code, more noise. Did I mention that I spent more time reading code?
  • Painless refactoring. Renaming a method should not break my tests.
That’s why I really like the syntax of EasyMock.

Long journey from EasyMock to Mockito

I was brought up on EasyMock. Normal kids got milk I got classes to test. Over the years on different projects I saw idyllic world of hand crafted stubs being overthrown by EasyMocks. On other project, jmock was doing fine until he got a Chuck’s roundhouse kick to the face by EasyMock. Finally, I saw resentment to EasyMock and triumphatic comeback of hand crafted stubs… Sometimes the resentment to EasyMock was a bit naive (“My class has 10 dependencies and is difficult to test. Therefore EasyMock sucks”). Sometimes it was clearly righteous…
Here is what I wanted to achieve with Mockito so that it suits me better in test-driving code the way I like:
tdd
Focused testing. Should let me focus test methods on specific behavior/interaction. Should minimize distractions like expecting/recording irrelevant interactions.
Separation of stubbing and verification. Should let me code in line with intuition: stub before execution, selectively verify interactions afterwards. I don’t want any verification-related code before execution.
Explicit language. Verification and stubbing code should be easy to discern, should distinguish from ordinary method calls / from any supporting code / assertions.
Simple stubbing model. Should bring the simplicity of good old hand crafted stubs without the burden of actually implementing a class. Rather than verifying stubs I want to focus on testing if stubbed value is used correctly.

Only one type of mock, one way of creating mocks. So that it’s easy to share setup.
No framework-supporting code. No record(), replay() methods, no alien control/context objects. These don’t bring any value to the game.
Slim API. So that anyone can use it efficiently and produce clean code. API should push back if someone is trying to do something too smart: if the class is difficult to test – refactor the class.
Explicit errors. Verification errors should always point stack trace to failed interaction. I want to click on first stack element and navigate to failed interaction.
Clean stack trace. Part of TDDing is reading stack traces. It’s Red-Green-Refactor after all – I’ve got stack trace when it’s red. Stack trace should always be clean and hide irrelevant internals of a library. Although modern IDE can help here, I’d rather not depend on IDE neither on competence in using IDE…
road split
EasyMock is a decent piece of software, credits go to kick-ass people who wrote it. Initial hacks on Mockito were done on top of the EasyMock code but since then I rewrote most of the codebase. Enjoy

Comments

Popular posts from this blog

Stretch a row if data overflows in jasper reports

It is very common that some columns of the report need to stretch to show all the content in that column. But  if you just specify the property " stretch with overflow' to that column(we called text field in jasper report world) , it will just stretch that column and won't change other columns, so the row could be ridiculous. Haven't find the solution from internet yet. So I just review the properties in iReport one by one and find two useful properties(the bold highlighted in example below) which resolve the problems.   example:
<band height="20" splitType="Stretch"> <textField isStretchWithOverflow="true" pattern="" isBlankWhenNull="true"> <reportElement stretchType="RelativeToTallestObject" mode="Opaque" x="192" y="0" width="183" height="20"/> <box leftPadding="2"> <pen lineWidth="0.25"/> …

JasperReports - Configuration Reference

Spring - Operations with jdbcTemplate

This class manages all the database communication and exception handling using a java.sql.Connection that is obtained from the provided DataSource. JdbcTemplate is a stateless and threadsafe class and you can safely instantiate a single instance to be used for each DAO.


Use of Callback Methods
JdbcTemplate is based on a template style of programming common to many other parts of Spring. Some method calls are handled entirely by the JdbcTemplate, while others require the calling class to provide callback methods that contain the implementation for parts of the JDBC workflow. This is another form of Inversion of Control. Your application code hands over the responsibility of managing the database access to the template class. The template class in turn calls back to your application code when it needs some detail processing filled in. These callback methods are allowed to throw a java.sql.SQLException, since the framework will be able to catch this exception and use its built-in excepti…