9b49ef433c
This documents the cleaned up package structure and explains how callbacks are invoked. Ginkgko v2 has led to some improvements in that area.
89 lines
3.5 KiB
Markdown
89 lines
3.5 KiB
Markdown
# Overview
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The Kubernetes E2E framework simplifies writing Ginkgo tests suites. It's main
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usage is for these tests suites in the Kubernetes repository itself:
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- test/e2e: runs as client for a Kubernetes cluster. The e2e.test binary is
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used for conformance testing.
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- test/e2e_node: runs on the same node as a kublet instance. Used for testing
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kubelet.
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- test/e2e_kubeadm: test suite for kubeadm.
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Usage of the framework outside of Kubernetes is possible, but not encouraged.
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Downstream users have to be prepared to deal with API changes.
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# Code Organization
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The core framework is the `k8s.io/kubernetes/test/e2e/framework` package. It
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contains functionality that all E2E suites are expected to need:
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- connecting to the apiserver
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- managing per-test namespaces
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- logging (`Logf`)
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- failure handling (`Fail`, `Failf`)
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- writing concise JUnit test results
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It also contains a `TestContext` with settings that can be controlled via
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command line flags. For historic reasons, this also contains settings for
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individual tests or packages that are not part of the core framework.
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Optional functionality is placed in sub packages like
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`test/e2e/framework/pod`. The core framework does not depend on those. Sub
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packages may depend on the core framework.
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The advantages of splitting the code like this are:
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- leaner go doc packages by grouping related functions together
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- not forcing all E2E suites to import all functionality
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- avoiding import cycles
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# Execution Flow
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When a test suite gets invoked, the top-level `Describe` calls register the
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callbacks that define individual tests, but does not invoke them yet. After
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that init phase, command line flags are parsed and the `Describe` callbacks are
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invoked. Those then define the actual tests for the test suite. Command line
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flags can be used to influence the test definitions.
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Now `Context/BeforeEach/AfterEach/It` define code that will be called later
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when executing a specific test. During this setup phase, `f :=
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framework.NewDefaultFramework("some tests")` creates a `Framework` instance for
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one or more tests. `NewDefaultFramework` initializes that instance anew for
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each test with a `BeforeEach` callback. Starting with Kubernetes 1.26, that
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instance gets cleaned up after all other code for a test has been invoked, so
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the following code is correct:
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```
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f := framework.NewDefaultFramework("some tests")
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ginkgo.AfterEach(func() {
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# Do something with f.ClientSet.
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}
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ginkgo.It("test something", func() {
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# The actual test.
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})
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```
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Optional functionality can be injected into each test by adding a callback to
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`NewFrameworkExtensions` in an init function. `NewDefaultFramework` will invoke
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those callbacks as if the corresponding code had been added to each test like this:
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```
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f := framework.NewDefaultFramework("some tests")
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optional.SomeCallback(f)
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```
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`SomeCallback` then can register additional `BeforeEach` or `AfterEach`
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callbacks that use the test's `Framework` instance.
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When a test runs, callbacks defined for it with `BeforeEach` and `AfterEach`
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are called in first-in-first-out order. Since the migration to ginkgo v2 in
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Kubernetes 1.25, the `AfterEach` callback is called also when there has been a
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test failure. This can be used to run cleanup code for a test
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reliably. However,
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[`ginkgo.DeferCleanup`](https://onsi.github.io/ginkgo/#spec-cleanup-aftereach-and-defercleanup)
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is often a better alternative. Its callbacks are executed in first-in-last-out
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order.
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`test/e2e/framework/internal/unittests/cleanup/cleanup.go` shows how these
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different callbacks can be used and in which order they are going to run.
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