The goal of this package is to provide a small framework to isolate the test
execution and safely check whether a test succeeds or fails as expected. In
combination with the mock
package it ensures that a test finishes
reliably and reports its failure even if a system under test is spawning
go-routines.
Use the following example to intercept and validate a panic using the isolated test environment.
func TestUnit(t *testing.T) {
test.Run(test.Success, func(t test.Test){
// Given
mocks := mock.NewMocks(t).Expect(
test.Panic("fail"),
)
// When
panic("fail")
...
})(t)
}
But there are many other supported use case, you can discover reading the below examples.
The test
framework supports to run isolated, parameterized, parallel tests
using a lean test runner. The runner can be instantiated with a single test
parameter set (test.Any
), a slice of test parameter sets (test.Slice
), or a
map of test case name to test parameter sets (test.Map
- preferred pattern).
The test is started by Run
that accepts a simple test function as input,
using a test.Test
interface, that is compatible with most tools, e.g.
gomock
.
func TestUnit(t *testing.T) {
test.Any|Slice|Map(t, testParams).
Filter("test-case-name", false|true).
Timeout(5*time.Millisecond).
StopEarly(time.Millisecond).
Run|RunSeq(func(t test.Test, param UnitParams){
// Given
// When
// Then
}).Cleanup(func(){
// clean test resources
})
}
This creates and starts a lean test wrapper using a common interface, that
isolates test execution and intercepts all failures (including panics), to
either forward or suppress them. The result is controlled by providing a test
parameter of type test.Expect
(name expect
) that supports test.Failure
(false) and Success
(true - default).
Similar a test case name can be provided using type test.Name
(name name
-
default value unknown-%d
) or as key using a test case name to parameter set
mapping.
Note: See Parallel tests requirements
for more information on requirements in parallel parameterized tests. If
parallel parameterized test are undesired, RunSeq
can be used to enforce a
sequential test execution.
It is also possible to select a subset of tests for execution by setting up a
Filter
using a regular expression to match or filter by the normalized test
name, or to set up a Timeout
as well as a grace period to StopEarly
for
giving the Cleanup
-functions sufficient time to free resources.
It is also possible to isolate only a single test step by setting up a small test function that is run in isolation.
func TestUnit(t *testing.T) {
test.Map(t, testParams).
Run|RunSeq(func(t test.Test, param UnitParams){
// Given
// When
test.InRun(test.Failure, func(t test.Test) {
...
})(t)
// Then
})
}
If the above pattern is not sufficient, you can create your own customized
parameterized, parallel, isolated test wrapper using the basic abstraction
test.Run|RunSeq(test.Success|Failure, func (t test.Test) {})
:
func TestUnit(t *testing.T) {
t.Parallel()
for name, param := range testParams {
name, param := name, param
t.Run(name, test.Run(param.expect, func(t test.Test) {
t.Parallel()
// Given
// When
// Then
}))
}
}
Or finally, use even more directly the flexible test.Context
that is
providing the features on top of the underlying test.Test
interface
abstraction, if you need more control about the test execution:
func TestUnit(t *testing.T) {
t.Parallel()
test.New(t, test.Success).
Timeout(5*time.Millisecond).
StopEarly(time.Millisecond).
Run(func(t test.Test){
// Given
// When
// Then
})(t)
}
Besides just capturing the failure in the isolated test environment, it is also
very simple possible to validate the failures/panics using the self installing
validator that is tightly integrated with the mock
framework.
func TestUnit(t *testing.T) {
test.Run(func(t test.Test){
// Given
mock.NewMocks(t).Expect(mock.Setup(
test.Errorf("fail"),
test.Fatalf("fail"),
test.FailNow(),
test.Panic("fail"),
))
// When
t.Errorf("fail")
...
// And one of the terminal calls.
t.Fatalf("fail")
t.FailNow()
panic("fail")
// Then
})(t)
}
Note: To enable panic testing, the isolated test environment is recovering from all panics by default and converting them in fatal error messages. This is often most usable and sufficient to fix the issue. If you need to discover the source of the panic, you need to spawn a new unrecovered go-routine.
Hint: gomock
uses very complicated reporting patterns that are
hard to recreate. Do not try it.
Setting up tests and comparing test results is most efficient, when you directly can set up and compare the actual objects. However, this is sometimes prevented by the objects not being open for construction and having private states.
To cope with this challenge the test
-package supports helpers to access, i.e.
read and write, private fields of objects using reflection.
test.NewBuilder[...]()
allows constructing a new object from scratch.test.NewGetter(...)
allows reading private fields of an object by name.test.NewSetter(...)
allows writing private fields by name, and finallytest.NewAccessor(...)
allows reading and writing of private fields by name.
The following example shows a real world example of how the private properties
of a closed error can be set up using the test.NewBuilder[...]()
.
err := test.NewBuilder[viper.ConfigFileNotFoundError]().
Set("locations", fmt.Sprintf("%s", "...path...")).
Set("name", "test").Build()
Similar we can set up input objects with private properties to minimize the dependencies in the test setup, however, using this features exposes the test to internal changes.
Currently, the package supports only one out-of-the-box test pattern to test
the main
-methods of commands.
testMainParams := map[string]test.MainParams{
"no mocks": {
Args: []string{"mock"},
Env: []string{},
ExitCode: 0,
},
}
func TestMain(t *testing.T) {
test.Map(t, testMainParams).Run(test.TestMain(main))
}
The pattern executes the main
-method in a separate process that setting up
the command line arguments (Args
) and modifying the environment variables
(Env
) and to capture and compare the exit code of the program execution.
Note: the general approach can be used to test any code calling os.Exit
,
however, it is focused on testing the main
-methods with and without parsing
command line arguments.