Go Interface Mocking Tool
source link: https://www.tuicool.com/articles/hit/ZjQVreQ
Go to the source link to view the article. You can view the picture content, updated content and better typesetting reading experience. If the link is broken, please click the button below to view the snapshot at that time.
Charlatan
Percolate's Go Interface Mocking Tool. Please read our introductory blog post .
Installation
go get github.com/percolate/charlatan
Usage
charlatan [options] <interface> ... charlatan -h | --help Options: -dir string input package directory [default: current package directory] -file value name of input file, may be repeated, ignored if -dir is present -output string output file path [default: ./charlatan.go] -package string output package name [default: "<current package>"]
If you would like the mock implementations to live in the same package as the interface definition then use the simplest invocation as a directive:
//go:generate charlatan Interface
or from the command line:
charlatan -file=path/to/file.go Interface
You can chose the output path using -output
, which must include the
name of the generated source file. Any intermediate directories in the
path that don't exist will be created. The package used in the
generated file's package
directive can be set using -package
.
Example
Given the following interface:
package example //go:generate charlatan Service type Service interface { Query(filter *QueryFilter) ([]*Thing, error) Fetch(id string) (*Thing, error) }
Running go generate ...
for the above package/file should produce
the file charlatan.go
:
package example type QueryInvocation struct { Parameters struct { Filter *QueryFilter } Results struct { Ident1 []*Thing Ident2 error } } type FetchInvocation struct { Parameters struct { Id string } Results struct { Ident3 *Thing Ident4 error } } type FakeService struct { QueryHook func(*QueryFilter) ([]*Thing, error) FetchHook func(string) (*Thing, error) QueryCalls []*QueryInvocation FetchCalls []*FetchInvocation } func (f *FakeService) Query(filter *QueryFilter) (id1 []*Thing, id2 error) { invocation := new(QueryInvocation) invocation.Parameters.Filter = filter id1, id2 := f.QueryHook(filter) invocation.Results.Ident1 = id1 invocation.Results.Ident2 = id2 return } // other generated code elided ...
Now you can use this in your tests by injecting the FakeService
implementation instead of the actual one. A FakeService
can be used
anywhere a Service
interface is expected.
func TestUsingService(t *testing.T) { // expectedThings := ... // expectedCriteria := ... svc := &example.FakeService{ QueryHook: func(filter *QueryFilter) ([]*Thing, error) { if filter.Criteria != expectedCriteria { t.Errorf("expected criteria value: %v, have: %v", filter.Criteria, expectedCriteria) return nil, errors.New("unexpected criteria") } return expectedThings, nil }, } // use the `svc` instance in the code under test ... // assert state of FakeService ... svc.AssertQueryCalledOnce(t) }
Create anonymous function implementations for only those interface methods that should be called in the code under test. This will force a panic if any unexpected calls are made to the mock implementation.
The generated code has godoc
formatted comments explaining the use
of the mock and its methods.
Recommend
About Joyk
Aggregate valuable and interesting links.
Joyk means Joy of geeK