Introduction to Hamcrest

Hamcrest library provides number of matchers to perform comparison operations. You can use hamcrest and junit libraries together to write effective test cases.

Hamcrest implementation is available in number of languages.

Java                                                             

Python

Ruby

Objective-C

PHP

Erlang

Swift

I am going to use below maven dependencies throughout this tutorial.

         <dependencies>

                 <!-- https://mvnrepository.com/artifact/junit/junit -->

                 <dependency>

                          <groupId>junit</groupId>

                          <artifactId>junit</artifactId>

                          <version>4.12</version>

                          <scope>test</scope>

                 </dependency>

                 <!-- https://mvnrepository.com/artifact/org.hamcrest/hamcrest-all -->

                 <dependency>

                          <groupId>org.hamcrest</groupId>

                          <artifactId>hamcrest-all</artifactId>

                          <version>1.3</version>

                          <scope>test</scope>

                 </dependency>

         </dependencies>

        

In this tutorial series, I am going to show you how to use hamcrest for unit testing.

Can I use Hamcrest with TestNG?

Yes, Hamcrest can be integrated with other testing frameworks like JUnit and TestNG.

Can I use Hamcrest with EasyMock?

yes, Hamcrest provides adaptors for EasyMock.

To make the programs more readable, import below packages.

import static org.hamcrest.MatcherAssert.assertThat;

import static org.hamcrest.Matcher.*;

Conventions

Test method always follow the convention like methodName_inputs_expectedOutputs

At the time of writing this tutorial, Hamcrest provides below matchers.

allOf

anyOf

both

either

describedAs

everyItem

is

isA

anything

hasItem

hasItems

equalTo

any

instanceOf

not

nullValue

notNullValue

sameInstance

theInstance

containsString

startsWith

endsWith

array

hasItemInArray

arrayContaining

arrayContainingInAnyOrder

arrayWithSize

emptyArray

hasSize

empty

emptyCollectionOf

emptyIterable

emptyIterableOf

contains

containsInAnyOrder

iterableWithSize

hasEntry

hasKey

hasValue

isIn

isOneOf

closeTo

comparesEqualTo

greaterThan

greaterThanOrEqualTo

lessThan

lessThanOrEqualTo

equalToIgnoringCase

equalToIgnoringWhiteSpace

isEmptyString

isEmptyOrNullString

stringContainsInOrder

typeCompatibleWith

eventFrom

hasProperty

samePropertyValuesAs

hasXPath

Reference

http://hamcrest.org/

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