gocheck

Introduction

The Go language provides an internal testing library, named testing, which is relatively slim due to the fact that the standard library correctness by itself is verified using it. The check package, on the other hand, expects the standard library from Go to be working correctly, and builds on it to offer a richer testing framework for libraries and applications to use.

gocheck includes features such as:

Helpful error reporting to aid on figuring problems out (see below)
Richer test helpers: assertions which interrupt the test immediately, deep multi-type comparisons, string matching, etc
Suite-based grouping of tests
Fixtures: per suite and/or per test set up and tear down
Benchmarks integrated in the suite logic (with fixtures, etc)
Management of temporary directories
Panic-catching logic, with proper error reporting
Proper counting of successes, failures, panics, missed tests, skips, etc
Explicit test skipping
Support for expected failures
Verbosity flag which disables output caching (helpful to debug hanging tests, for instance)
Multi-line string reporting for more comprehensible failures
Inclusion of comments surrounding checks on failure reports
Fully tested (it manages to test itself reliably)

Compatibility with "go test"

gocheck works as an extension to the testing package and to the "go test" runner. That allows keeping all current tests and using gocheck-based tests right away for new tests without conflicts. The gocheck API was purposefully made similar to the testing package for a smooth migration.

Installing and updating

Install gocheck's check package with the following command:


go get gopkg.in/check.v1

To ensure you're using the latest version, run the following instead:


go get -u gopkg.in/check.v1

API documentation

The API documentation for gocheck's check package is available online at:

https://gopkg.in/check.v1

Basic example

Here is a simple example of how to use gocheck.


package hello_test

import (
    "testing"
    "io"

    . "gopkg.in/check.v1"
)

// Hook up gocheck into the "go test" runner.
func Test(t *testing.T) { TestingT(t) }

type MySuite struct{}

var _ = Suite(&MySuite{})

func (s *MySuite) TestHelloWorld(c *C) {
    c.Assert(42, Equals, "42")
    c.Assert(io.ErrClosedPipe, ErrorMatches, "io: .*on closed pipe")
    c.Check(42, Equals, 42)
}

See Assertions and verifications below for more information on these tests.

Using fixtures

Fixtures are available by using one or more of the following methods in a test suite:

func (s *SuiteType) SetUpSuite(c *C) - Run once when the suite starts running.
func (s *SuiteType) SetUpTest(c *C) - Run before each test or benchmark starts running.
func (s *SuiteType) TearDownTest(c *C) - Run after each test or benchmark runs.
func (s *SuiteType) TearDownSuite(c *C) - Run once after all tests or benchmarks have finished running.

Here is an example preparing some data in a temporary directory before each test runs:


type Suite struct{
    dir string
}

func (s *MySuite) SetUpTest(c *C) {
    s.dir = c.MkDir()
    // Use s.dir to prepare some data.
}

func (s *MySuite) TestWithDir(c *C) {
    // Use the data in s.dir in the test.
}

Adding benchmarks

Benchmarks may be added by prefixing a method in the suite with Benchmark. The method will be called with the usual *C argument, but unlike a normal test it is supposed to put the benchmarked logic within a loop iterating c.N times.

For example:


func (s *MySuite) BenchmarkLogic(c *C) {
    for i := 0; i < c.N; i++ {
        // Logic to benchmark
    }
}

These methods are only run when in benchmark mode, using the -check.b flag, and will present a result similar to the following when run:


PASS: myfile.go:67: MySuite.BenchmarkLogic       100000    14026 ns/op
PASS: myfile.go:73: MySuite.BenchmarkOtherLogic  100000    21133 ns/op

All the fixture methods are run as usual for a test method.

To obtain the timing for normal tests, use the -check.v flag instead.

Skipping tests

Tests may be skipped with the Skip method within SetUpSuite, SetUpTest, or the test method itself. This allows selectively ignoring tests based on custom factors such as the architecture being run, flags provided to the test, or the availbility of resources (network, etc).

As an example, the following test suite will skip all the tests within the suite unless the -live option is provided to go test:


var live = flag.Bool("live", false, "Include live tests")

type LiveSuite struct{}

func (s *LiveSuite) SetUpSuite(c *C) {
    if !*live {
        c.Skip("-live not provided")
    }
}

Running tests and output sample

Use the go test tool as usual to run the tests:


$ go test

----------------------------------------------------------------------
FAIL: hello_test.go:16: S.TestHelloWorld

hello_test.go:17:
    c.Check(42, Equals, "42")
... obtained int = 42
... expected string = "42"

hello_test.go:18:
    c.Check(io.ErrClosedPipe, ErrorMatches, "BOOM")
... error string = "io: read/write on closed pipe"
... regex string = "BOOM"


OOPS: 0 passed, 1 FAILED
--- FAIL: hello_test.Test
FAIL

Assertions and checks

gocheck uses two methods of *C to verify expectations on values obtained in test cases: Assert and Check. Both of these methods accept the same arguments, and the only difference between them is that when Assert fails, the test is interrupted immediately, while Check will fail the test, return false, and allow it to continue for further checks.

Assert and Check have the following types:


func (c *C) Assert(obtained interface{}, chk Checker, ...args interface{})
func (c *C) Check(obtained interface{}, chk Checker, ...args interface{}) bool

They may be used as follows:


func (s *S) TestSimpleChecks(c *C) {
    c.Assert(value, Equals, 42)
    c.Assert(s, Matches, "hel.*there")
    c.Assert(err, IsNil)
    c.Assert(foo, Equals, bar, Commentf("#CPUs == %d", runtime.NumCPU())
}

The last statement will display the provided message next to the usual debugging information, but only if the check fails.

Custom verifications may be defined by implementing the Checker interface. There are several standard checkers available. See the documtation for details and examples:

https://gopkg.in/check.v1#Checker

Selecting which tests to run

gocheck can filter tests out based on the test name, the suite name, or both. To run tests selectively, provide the command line option -check.f when running go test. Note that this option is specific to gocheck, and won't affect go test itself.

Some examples:


$ go test -check.f MyTestSuite
$ go test -check.f "Test.*Works"
$ go test -check.f "MyTestSuite.Test.*Works"

Verbose modes

gocheck offers two levels of verbosity through the -check.v and -check.vv flags. In the first mode, passing tests will also be reported. The second mode will disable log caching entirely and will stream starting and ending suite calls and everything logged in between straight to the output. This is useful to debug hanging tests, for instance.

License

gocheck is made available under the Simplified BSD License.