go-vcr
go-vcr
simplifies testing by recording your HTTP interactions and
replaying them in future runs in order to provide fast, deterministic
and accurate testing of your code.
go-vcr
was inspired by the VCR library for Ruby.
Installation
Install go-vcr
by executing the command below:
$ go get github.com/dnaeon/go-vcr/recorder
Usage
Here is a simple example of recording and replaying
etcd HTTP interactions.
You can find other examples in the example
directory of this
repository as well.
package main
import (
"log"
"time"
"github.com/dnaeon/go-vcr/recorder"
"github.com/coreos/etcd/client"
"golang.org/x/net/context"
)
func main() {
r, err := recorder.New("fixtures/etcd")
if err != nil {
log.Fatal(err)
}
defer r.Stop()
cfg := client.Config{
Endpoints: []string{"http://127.0.0.1:2379"},
HeaderTimeoutPerRequest: time.Second,
Transport: r,
}
c, err := client.New(cfg)
if err != nil {
log.Fatalf("Failed to create etcd client: %s", err)
}
etcdKey := "/foo"
kapi := client.NewKeysAPI(c)
resp, err := kapi.Get(context.Background(), etcdKey, nil)
if err != nil {
log.Fatalf("Failed to get etcd key %s: %s", etcdKey, err)
}
log.Printf("Successfully retrieved etcd key %s: %s", etcdKey, resp.Node.Value)
}
Custom Request Matching
During replay mode, You can customize the way incoming requests are
matched against the recorded request/response pairs by defining a
Matcher function. For example, the following matcher will match on
method, URL and body:
r, err := recorder.New("fixtures/matchers")
if err != nil {
log.Fatal(err)
}
defer r.Stop()
r.SetMatcher(func(r *http.Request, i cassette.Request) bool {
if r.Body == nil {
return cassette.DefaultMatcher(r, i)
}
var b bytes.Buffer
if _, err := b.ReadFrom(r.Body); err != nil {
return false
}
r.Body = ioutil.NopCloser(&b)
return cassette.DefaultMatcher(r, i) && (b.String() == "" || b.String() == i.Body)
})
Protecting Sensitive Data
You often provide sensitive data, such as API credentials, when making
requests against a service.
By default, this data will be stored in the recorded data but you probably
don't want this.
Removing or replacing data before it is stored can be done by adding one or
more Filter
s to your Recorder
.
Here is an example that removes the Authorization
header from all requests:
r, err := recorder.New("fixtures/filters")
if err != nil {
log.Fatal(err)
}
defer r.Stop()
r.AddFilter(func(i *cassette.Interaction) error {
delete(i.Request.Headers, "Authorization")
return nil
})
Sensitive data in responses
Filters added using *Recorder.AddFilter
are applied within VCR's custom http.Transport
. This means that if you edit a response in such a filter then subsequent test code will see the edited response. This may not be desirable in all cases. For instance, if a response body contains an OAuth access token that is needed for subsequent requests, then redact the access token in SaveFilter
will result in authorization failures.
Another way to edit recorded interactions is to use *Recorder.AddSaveFilter
. Filters added with this method are applied just before interactions are saved when *Recorder.Stop
is called.
r, err := recorder.New("fixtures/filters")
if err != nil {
log.Fatal(err)
}
defer r.Stop()
r.AddSaveFilter(func(i *cassette.Interaction) error {
if strings.Contains(i.URL, "/oauth/token") {
i.Response.Body = `{"access_token": "[REDACTED]"}`
}
return nil
})
Passing Through Requests
Sometimes you want to allow specific requests to pass through to the remote
server without recording anything.
Globally, you can use ModeDisabled
for this, but if you want to disable the
recorder for individual requests, you can add Passthrough
functions to the
recorder. The function takes a pointer to the original request, and returns a
boolean, indicating if the request should pass through to the remote server.
Here's an example to pass through requests to a specific endpoint:
r.AddPassthrough(func(req *http.Request) bool {
return req.URL.Path == "/login"
})
License
go-vcr
is Open Source and licensed under the
BSD License