Spock VW: Writing Custom Spock Framework Extensions
In some engineering branches, rigorous tests must pass only an external audit; Spock VW extension makes sure all tests pass on a Continuous Integration server
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Join For FreeSpock framework has multiple built-in extensions that support many core features like:
@Ignore
, @Timeout
and annotations. But more importantly developers are encouraged to write their own extensions. For example, the SpringExtension nicely integrates Spock with Spring framework. Writing custom extensions is not very well documented. In this article we will write very simple extension. It is not a comprehensive guide but just a funny showcase.
Introducing Spock VW Extension
Spock VW extension makes sure all tests pass on CI server, even if they fail on developers machine or on production. The idea is heavily inspired by phpunit-vw. Let's take this simple, completely made up test that can't possibly succeed:
@Unroll
class EmissionsSpec extends Specification {
def 'nitrogen oxide emission (#emission) in #model must not exceed #allowed'() {
expect:
emission <= allowed
where:
model | emission || allowed
'Jetty' | 1.5 || 0.022
'Pascal' | 0.67 || 0.016
}
def 'carbon dioxide'() {
expect:
105 < 130
}
}
First test obviously fails for both samples, but we can transparently add a Spock extension that will make sure no CI server ever catches this issue. The extension simply examines all system properties and environment variables, trying to discover if the host environment is actually a CI server:
package com.nurkiewicz.vw
import org.spockframework.runtime.extension.IGlobalExtension
import org.spockframework.runtime.model.SpecInfo
class VwExtension implements IGlobalExtension {
private static final CONTROLLED_ENV = [
'bamboo.buildKey',
'BUILD_ID', 'BUILD_NUMBER', 'BUILDKITE',
'CI', 'CIRCLECI',
'CONTINUOUS_INTEGRATION',
'GOCD_SERVER_HOST',
'HUDSON_URL', 'JENKINS_URL',
'TEAMCITY_VERSION',
'TRAVIS',
]
private static final boolean EVERYTHING_IS_FINE =
CONTROLLED_ENV.any {prop ->
System.getProperty(prop) || System.getenv(prop)}
@Override
void visitSpec(SpecInfo spec) {
if (EVERYTHING_IS_FINE) {
spec.features*.skipped = true
}
}
}
VwExtension
is like an aspect around every Specification
you have in your codebase. It examines a list of known environment variables and if any()
of them is present (EVERYTHING_IS_FINE
constant), all
features
(tests) within this Spec
are skipped. One more thing. Extensions are not discovered automatically, you must create org.spockframework.runtime.extension.IGlobalExtension
in: META-INF
; directory on the CLASSPATH
(of course it can be in a different JAR). The content of that file is simply a fully qualified name of the extension class, e.g.
com.nurkiewicz.vw.VwExtension
That's about it, happy testing!
Published at DZone with permission of Tomasz Nurkiewicz, DZone MVB. See the original article here.
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