GitHub - percolate/charlatan: Go Interface Mocking Tool
source link: https://github.com/percolate/charlatan
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README.md
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 interace 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 pacakge
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 FetechInvocation 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 text ... // 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 painc 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.
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