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FEST-Assert is a Java library that provides a fluent interface for writing assertions. Its main goal is to improve test code readability and make maintenance of tests easier.
FEST-Assert requires Java SE 5.0 or later and can be used with either JUnit or TestNG.
Currently, this module provides assertions for the following data types:
ObjectStringCollectionMapboolean, int, char, etc.)ObjectBufferedImageThrowableFileBigDecimalIt can be downloaded here. For Maven 2 users, details about the project's repository can be found at here.
We have written a migration guide to easily replace JUnit assertions with Fest assertions, check here.
Some simple example to start.
import static org.fest.assertions.Assertions.assertThat;
int removed = employees.removeFired();
assertThat(removed).isZero();
List<Employee> newEmployees = employees.hired(TODAY);
assertThat(newEmployees).hasSize(6)
.contains(frodo, sam);
String[] newHires = employees.newHiresNames();
assertThat(newHires).containsOnly("Gandalf", "Arwen", "Gimli");
assertThat(yoda).isInstanceOf(Jedi.class)
.isEqualTo(foundJedi)
.isNotEqualTo(foundSith);
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The full example file is FestAssertExamples.java, you should be able to copy it in your IDE and run it successfully as JUnit tests.
import static org.fest.assertions.Assertions.assertThat;
import static org.fest.assertions.MapAssert.entry;
@Before
public void setup() {
// let's do some team building :)
fellowshipOfTheRing.add(frodo);
fellowshipOfTheRing.add(sam);
fellowshipOfTheRing.add(merry);
fellowshipOfTheRing.add(pippin);
fellowshipOfTheRing.add(gandalf);
fellowshipOfTheRing.add(legolas);
fellowshipOfTheRing.add(gimli);
fellowshipOfTheRing.add(aragorn);
fellowshipOfTheRing.add(boromir);
// ring bearers
ringBearers.put(Ring.nenya, galadriel);
ringBearers.put(Ring.narya, gandalf);
ringBearers.put(Ring.vilya, elrond);
ringBearers.put(Ring.oneRing, frodo);
}
@Test
public void basic_assertions_examples() {
assertThat(frodo.getAge()).isEqualTo(33);
assertThat(frodo.getName()).isEqualTo("Frodo");
}
@Test
public void list_assertions_examples() {
assertThat(fellowshipOfTheRing).hasSize(9)
.contains(frodo, sam)
.excludes(sauron);
fellowshipOfTheRing.clear();
assertThat(fellowshipOfTheRing).isEmpty();
}
@Test
public void onProperty_usage() {
// with simple property
assertThat(fellowshipOfTheRing).onProperty("name")
.contains("Boromir", "Gandalf", "Frodo", "Legolas")
.excludes("Sauron", "Elrond");
// with simple property on Race
assertThat(fellowshipOfTheRing).onProperty("race")
.contains(hobbit, man, elf)
.excludes(orc);
// nested property introspection on Race
assertThat(fellowshipOfTheRing).onProperty("race.name")
.contains("Hobbit", "Man", "Elf")
.excludes("Orc");
}
@Test
public void exceptions_assertions_examples() {
assertThat(fellowshipOfTheRing).hasSize(9);
try {
fellowshipOfTheRing.get(9); // argggl !
} catch (Exception e) {
assertThat(e).isInstanceOf(IndexOutOfBoundsException.class)
.hasMessage("Index: 9, Size: 9")
.hasNoCause();
}
}
@Test
public void map_assertions_examples() {
assertThat(ringBearers).hasSize(4)
.includes(entry(Ring.oneRing, frodo), entry(Ring.nenya, galadriel))
.excludes(entry(Ring.oneRing, aragorn));
}
@Test
public void number_assertions_examples() throws Exception {
assertThat(gandalf.getAge()).isGreaterThan(frodo.getAge());
File emptyFile = writeFile("emptyFile", "");
assertThat(emptyFile.length()).isZero();
// another way to assert file size/length
assertThat(emptyFile).hasSize(0);
}
@Test
public void file_assertions_examples() throws Exception {
File xFile = writeFile("xFile", "The Truth Is Out There");
File xFileClone = writeFile("xFileClone", "The Truth Is Out There");
assertThat(xFile).exists()
.isFile()
.hasSameContentAs(xFileClone)
.isRelative()
.hasSize(22);
}
// fields initialization
private final Race hobbit = new Race("Hobbit", false);
private final Race maia = new Race("Maia", true);
private final Race man = new Race("Man", false);
private final Race elf = new Race("Elf", true);
private final Race dwarf = new Race("Dwarf", false);
private final Race orc = new Race("Orc", false);
private final Character frodo = new Character("Frodo", 33, hobbit);
private final Character sam = new Character("Sam", 38, hobbit);
private final Character merry = new Character("Merry", 36, hobbit);
private final Character pippin = new Character("Pippin", 28, hobbit);
private final Character gandalf = new Character("Gandalf", 2020, maia);
private final Character gimli = new Character("Gimli", 139, dwarf);
private final Character legolas = new Character("Legolas", 1000, elf);
private final Character aragorn = new Character("Aragorn", 87, man);
private final Character boromir = new Character("Boromir", 87, man);
private final Character sauron = new Character("Sauron", 50000, maia);
private final Character galadriel = new Character("Legolas", 3000, elf);
private final Character elrond = new Character("Legolas", 3000, elf);
private final List<Character> fellowshipOfTheRing = new ArrayList<Character>();
private final Map<Ring, Character> ringBearers = new HashMap<Ring, Character>();
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Here's a list of find/replace based on regexp that allow to change JUnit assertion into Fest assertion (don't forget to check regexp mode in your editor replace window).
Changing
{highlight:yellow}*{_}assertEquals(0, myList.size())_*{highlight} |
{highlight:yellow}Changing assertEquals(0, myList.size()) to assertThat(myList).isEmpty(){highlight} |
assertEquals(0,(.*).size()); -> assertThat(\1).isEmpty(); |
It's important to run this one before the assertEquals -> isEqualTo, to avoid ending with : assertThat(myList.size()).isEqualTo(0)
Changing assertEquals(expectedSize, myList.size()) to assertThat(myList).hasSize(expectedSize)
{highlight:yellow}Changing assertEquals(expectedSize, myList.size()) to assertThat(myList).hasSize(expectedSize){highlight} |
assertEquals((.*),(*.).size()); -> assertThat(\2).hasSize(\1); |
It's important to run this one before the assertEquals -> isEqualTo, to avoid ending with : assertThat(myList.size()).isEqualTo(expectedSize)
Changing assertEquals(value, valueUnderTest) to assertThat(valueUnderTest).isEqualTo(value)
assertEquals((.),(.)); -> assertThat(\2).isEqualTo(\1); |
Changing assertNotEquals(value, valueUnderTest) to assertThat(valueUnderTest).isNotEqualTo(value)
assertNotEquals((.),(.)); -> assertThat(\2).isNotEqualTo(\1); |
Changing assertNull(objectUnderTest) to assertThat(objectUnderTest).isNull()
assertNull((.*)); -> assertThat(\1).isNull(); |
Changing assertNotNull(objectUnderTest) to assertThat(objectUnderTest).isNotNull()
assertNotNull((.*)); -> assertThat(\1).isNotNull(); |
Changing assertTrue(logicalCondition) to assertThat(logicalCondition).isTrue()
assertTrue((.*)); -> assertThat(\1).isTrue(); |
Changing assertFalse(logicalCondition) to assertThat(logicalCondition).isFalse()
assertFalse((.*)); -> assertThat(\1).isFalse(); |
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