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Refactoring JUnit TestsFranziska Sauerwein @Singsalad
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Setup (find a pair!)
install IDE (USB)import/download projectrun ConferenceTest
https://github.com/franziskas/RefactoringJUnitTests
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The problem: Tests that are
complex to readhard to maintaintake a long time to run
-> Tests lose their value4
Some reasons for this:
complex object modelsbad code designuse of external resources
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What we can do (short term)
simplify setup & assertionsclean test codeseparate dependencies
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Builder
hides irrelevant dataallows easy changes to testdefaults (e.g. new validation)simplifies creation & enablereuse
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Matcher
increases test readabilityimproves test failure messageis combinable & reusable
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Combining Matchers
allOf(..)
anyOf(..)
not(..)9
Object Matchers
equalTo(..) / sameInstance(..)
instanceOf(..) / isCompatibleType(..)
notNullValue(..) / nullValue(..)
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Collection Matchers
array(..) / hasItemInArray(..)
hasEntry(..) / hasKey(..) / hasValue(..)
hasItem(..), hasItems(..)
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Number Matchers
closeTo(..)
greaterThan(..) / greaterThanOrEqualTo(..)
lessThan(..) / lessThanOrEqualTo(..)
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String Matchers
equalToIgnoringCase(..)
equalToIgnoringWhiteSpace(..)
containsString(..)
endsWith(..) / startsWith(..)13
Custom Matchersprivate Matcher<User> hasEmail() { return new TypeSafeDiagnosingMatcher<Foo>() {
@Override public void describeTo(final Description description) { description.appendText("expected user to have an email"); } @Override protected boolean matchesSafely(final User user, final Description mismatchDescription) { mismatchDescription .appendText(" was ") .appendValue(user.getEmail();
return user.getEmail()!= null && user.getEmail().length() > 3;} };}
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Custom Matchersprivate Matcher<User> hasEmail() { return new TypeSafeDiagnosingMatcher<Foo>() {
@Override public void describeTo(final Description description) { description.appendText("expected user to have an email"); } @Override protected boolean matchesSafely(final User user, final Description mismatchDescription) { mismatchDescription .appendText(" was ") .appendValue(user.getEmail();
return user.getEmail()!= null && user.getEmail().length() > 3;} };}
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Custom Matchersprivate Matcher<User> hasEmail() { return new TypeSafeDiagnosingMatcher<Foo>() {
@Override public void describeTo(final Description description) { description.appendText("expected user to have an email"); } @Override protected boolean matchesSafely(final User user, final Description mismatchDescription) { mismatchDescription .appendText(" was ") .appendValue(user.getEmail();
return user.getEmail()!= null && user.getEmail().length() > 3;} };}
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Custom Matchersprivate Matcher<User> hasEmail() { return new TypeSafeDiagnosingMatcher<Foo>() {
@Override public void describeTo(final Description description) { description.appendText("expected user to have an email"); } @Override protected boolean matchesSafely(final User user, final Description mismatchDescription) { mismatchDescription .appendText(" was ") .appendValue(user.getEmail();
return user.getEmail()!= null && user.getEmail().length() > 3;} };}
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www.marcphilipp.de/blog/2013/01/02/hamcrest-quick-reference/
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Modularisation
one test - one concernunit tests for functionalitylarger tests for journey
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Summary
fix the code designin the meantime, ease the paintreat test code at least as well asproduction code
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Try it yourself!
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