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https://github.com/percolate/charlatan
Go Interface Mocking Tool
https://github.com/percolate/charlatan
code-generation go interfaces mock testing testing-tools
Last synced: about 2 months ago
JSON representation
Go Interface Mocking Tool
- Host: GitHub
- URL: https://github.com/percolate/charlatan
- Owner: percolate
- License: bsd-3-clause
- Created: 2017-10-06T21:55:14.000Z (about 7 years ago)
- Default Branch: master
- Last Pushed: 2023-11-19T22:35:01.000Z (about 1 year ago)
- Last Synced: 2024-07-31T20:52:56.764Z (4 months ago)
- Topics: code-generation, go, interfaces, mock, testing, testing-tools
- Language: Go
- Size: 2.75 MB
- Stars: 201
- Watchers: 51
- Forks: 10
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Codeowners: .github/CODEOWNERS
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README
# Charlatan
[](https://circleci.com/gh/percolate/charlatan)
[](https://codecov.io/github/percolate/charlatan?branch=master)
[](https://github.com/percolate/charlatan/blob/master/LICENSE)
[](https://goreportcard.com/report/github.com/percolate/charlatan)
Percolate's Go Interface Mocking Tool. Please read our [introductory blog post](https://medium.com/percolate-engineering/introducing-charlatan-df9b5d3d3107).
## Installation
go get github.com/percolate/charlatan
## Usage
```
charlatan [options] ...
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: ""]
```
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:
```go
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`:
```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.
```go
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.