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\author{Alexandre Rosano}
\pdfinfo{
  /Title (unit-testing.pdf)
  /Creator (Cheatography)
  /Author (Alexandre Rosano)
  /Subject (Unit testing Cheat Sheet)
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        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Unit testing Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{Alexandre Rosano} via \textcolor{DarkBackground}{\uline{cheatography.com/193992/cs/40417/}}}
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  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}Alexandre Rosano \\
  \uline{cheatography.com/alexandre-rosano} \\
  \end{tabulary}
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Published 6th October, 2023.\\
   Updated 5th August, 2024.\\
   Page {\thepage} of \pageref{LastPage}.
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
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  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
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\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{About unit testing}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Production code cleanliness cannot be greater than {\bf{test code cleanliness}}.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Test code cleanliness mainly depends on its {\bf{readability}}.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Unit tests can be viewed as {\bf{specifications}} of the system.} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{FIRST principles}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{{\bf{F}}ast : tests should be {\bf{fast}}. If they're slow, they won't be run.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{I}}ndependant : tests should {\bf{not depend on each other}}, otherwise their result will be hard to analyze.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{R}}epeatable : tests should be {\bf{repeatable in any environnement}}. Their execution should not depend on the availability of a specific environnement.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{S}}elf-Validating : tests should {\bf{either pass or fail}}. Evaluating their result mustn't be subjective.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{T}}imely : tests should be written {\bf{just before}} the {\bf{production code}} is written. If they're written after, they will be difficult to write.} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Test Driven Development}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Test Driven Developement}} is a great way to write unit test in a {\bf{timely manner}} and achieve a good {\bf{mutation score}}.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{1st rule}} : you may not write production code until you have written a failing unit test.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{2nd rule}} : you may not write more of a unit test than is sufficient to fail, and not compiling is failing.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{3rd rule}} : you may not write more production code than is sufficient to pass the currently failing test.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Obvious implementation}} : just {\bf{write it}} and see if the tests pass.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{ Triangulate }} : {\bf{drive}} implementation by using a set of {\bf{several examples}}.} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{General rules}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{{\bf{One test equals one behavior}}.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Write tests at the {\bf{uppermost level}} of code. Changing implementation details should not break a test, only a {\bf{new behavioral need}} (or a bug!) should.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Use {\bf{contract testing}} to write {\bf{accurate assertions}} and {\bf{reuse them}} between several implementations tests.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Name}} tests in a {\bf{fluent way}} or use the {\bf{pattern "Given - When - Then"}}} \tn 
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% Row 4
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\mymulticolumn{1}{x{5.377cm}}{The {\bf{body}} of test methods should clearly show the {\bf{pattern "Given - When - Then"}}.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{"Hide wires"}} : {\bf{boilerplate}} or {\bf{technical}} code irrelevent to understanding a test should be {\bf{hidden}}.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Hide irrelevant functional data}}. It is {\bf{noise}} that lowers the test understandability.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Abstract {\bf{magic values}} by giving them {\bf{meaningful names}}. It makes tests more understandable.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Do {\bf{not}} duplicate {\bf{production logic}}. If the logic has a bug, it will be duplicated, making the test useless.} \tn 
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% Row 9
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\mymulticolumn{1}{x{5.377cm}}{Do {\bf{not}} use {\bf{conditional logic}}. It lowers the readability of the test. {\bf{Split}} the test instead.} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Test doubles}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Dummy}} : {\bf{fixed values}} {\bf{not used}} by tests.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{ Stub }} : {\bf{fixed values}} {\bf{used}} by tests.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{ Fake }} : {\bf{dynamic values}} {\bf{used}} by tests.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{ Spy }} : {\bf{fixed values}} {\bf{used}} by test ; provides {\bf{data}} to {\bf{inspect its behavior}}.} \tn 
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% Row 4
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\mymulticolumn{1}{x{5.377cm}}{{\bf{ Mock }} : {\bf{fixed values}} {\bf{used}} by test ; provides {\bf{methods}} to {\bf{inspect its behavior}}.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Only use tests doubles {\bf{when necessary}}. Do not over use them as it will {\bf{lower the readability}} and {\bf{maintainability}} of the tests.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Use {\bf{"manually created"}} {\bf{fakes}} {\bf{most of the time}}. They are {\bf{reusable}}, {\bf{decouple}} test code from production code and {\bf{discourage}} the use of assertions {\bf{based on behavior}}.} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Assertions}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Prefer {\bf{assertions based on states}} over assertions based on behavior. The later are less maintainable as they {\bf{couple}} test code to production code.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Use an {\bf{expressive}} assertion {\bf{framework}}. Assertions should be understable quickly.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Only make assertions {\bf{regarding current case}}. Tests should only fail regarding their case expectations.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Do {\bf{not}} {\bf{aggregate}} assertions, as the cause of a failing test would be hard to spot.} \tn 
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% Row 4
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\mymulticolumn{1}{x{5.377cm}}{Assert {\bf{exceptions}} as they also are {\bf{specifications}} of the system.} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Testing approaches}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Use {\bf{property-based testing}} to {\bf{spot values}} that don't produce expected output.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Property-based testing}} and traditional {\bf{example-based testing}} are {\bf{complementary}}.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Use {\bf{"golden master testing"}} to take a snapshot of {\bf{legacy code}} outputs before {\bf{refactoring}} it.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Parameterized tests}} can help dealing with {\bf{edge values}}, by using a set of values covering the edges.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{When {\bf{fixing a bug}}, {\bf{start by writing a test}} that shows it exists, then fix the bug.} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Metrics}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Do not rely on code coverage alone}} : it only shows if production code is executed by the tests.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Use {\bf{mutation testing}} over {\bf{code coverage}} to evaluate unit tests effectiveness.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Mutation testing}} also helps having a {\bf{minimal production code}}, less production code meaning less possible mutations.} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Credits}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{\{\{bl\}\}Test doubles definitions inspired from this \{\{link="https://blog.cleancoder.com/uncle-bob/2014/05/14/TheLittleMocker.html"\}\}post\{\{/link\}\} by Robert C. Martin} \tn 
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% That's all folks
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