I am trying to test some golang code and I have a method that calls several other methods from its body. All these methods perform some kind of operations using an elastic search client. I wanted to know whether it will be a good practice if I used a test server for testing this method that will write different responses depending upon the request method and path it received from the request that is made when the methods inside the body execute and make calls to the elasticsearch client that sends the requests to my test server?
Update:
I am testing an elasticsearch middleware. It implements a reindex service like this
type reindexService interface {
reindex(ctx context.Context, index string, mappings, settings map[string]interface{}, includes, excludes, types []string) error
mappingsOf(ctx context.Context, index string) (map[string]interface{}, error)
settingsOf(ctx context.Context, index string) (map[string]interface{}, error)
aliasesOf(ctx context.Context, index string) ([]string, error)
createIndex(ctx context.Context, name string, body map[string]interface{}) error
deleteIndex(ctx context.Context, name string) error
setAlias(ctx context.Context, index string, aliases ...string) error
getIndicesByAlias(ctx context.Context, alias string) ([]string, error)
}
I can easily test all the methods using this pattern. Creating a simple elastic search client using a httptest server url and making requests to that server
var createIndexTests = []struct {
setup *ServerSetup
index string
err string
}{
{
&ServerSetup{
Method: "PUT",
Path: "/test",
Body: `null`,
Response: `{"acknowledged": true, "shards_acknowledged": true, "index": "test"}`,
},
"test",
"",
},
// More test cases here
}
func TestCreateIndex(t *testing.T) {
for _, tt := range createIndexTests {
t.Run("Should successfully create index with a valid setup", func(t *testing.T) {
ctx := context.Background()
ts := buildTestServer(t, tt.setup)
defer ts.Close()
es, _ := newTestClient(ts.URL)
err := es.createIndex(ctx, tt.index, nil)
if !compareErrs(tt.err, err) {
t.Fatalf("Index creation should have failed with error: %v got: %v instead
", tt.err, err)
}
})
}
}
But in case of reindex method this approach poses a problem since reindex makes calls to all the other methods inside its body. reindex looks something like this:
func (es *elasticsearch) reindex(ctx context.Context, indexName string, mappings, settings map[string]interface{}, includes, excludes, types []string) error {
var err error
// Some preflight checks
// If mappings are not passed, we fetch the mappings of the old index.
if mappings == nil {
mappings, err = es.mappingsOf(ctx, indexName)
// handle err
}
// If settings are not passed, we fetch the settings of the old index.
if settings == nil {
settings, err = es.settingsOf(ctx, indexName)
// handle err
}
// Setup the destination index prior to running the _reindex action.
body := make(map[string]interface{})
body["mappings"] = mappings
body["settings"] = settings
newIndexName, err := reindexedName(indexName)
// handle err
err = es.createIndex(ctx, newIndexName, body)
// handle err
// Some additional operations
// Reindex action.
_, err = es.client.Reindex().
Body(reindexBody).
Do(ctx)
// handle err
// Fetch all the aliases of old index
aliases, err := es.aliasesOf(ctx, indexName)
// handle err
aliases = append(aliases, indexName)
// Delete old index
err = es.deleteIndex(ctx, indexName)
// handle err
// Set aliases of old index to the new index.
err = es.setAlias(ctx, newIndexName, aliases...)
// handle err
return nil
}
For testing the reindex method I have tried mocking and DI but that turns out to be hard since the methods are defined on a struct instead of passing an interface as an argument to them. (So now I want to keep the implementation same since it would require making changes to all the plugin implementations and I want to avoid that)
I wanted to know whether I can use a modified version of my build server funtion (the one I am using is given below) to return responses for different methods for the reindex service which will write the appropriate responses based on the HTTP method and the request path that is used by that method?
type ServerSetup struct {
Method, Path, Body, Response string
HTTPStatus int
}
// This function is a modified version of: https://github.com/github/vulcanizer/blob/master/es_test.go
func buildTestServer(t *testing.T, setup *ServerSetup) *httptest.Server {
handlerFunc := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
requestBytes, _ := ioutil.ReadAll(r.Body)
requestBody := string(requestBytes)
matched := false
if r.Method == setup.Method && r.URL.EscapedPath() == setup.Path && requestBody == setup.Body {
matched = true
if setup.HTTPStatus == 0 {
w.WriteHeader(http.StatusOK)
} else {
w.WriteHeader(setup.HTTPStatus)
}
_, err := w.Write([]byte(setup.Response))
if err != nil {
t.Fatalf("Unable to write test server response: %v", err)
}
}
// TODO: remove before pushing
/*if !reflect.DeepEqual(r.URL.EscapedPath(), setup.Path) {
t.Fatalf("wanted: %s got: %s
", setup.Path, r.URL.EscapedPath())
}*/
if !matched {
t.Fatalf("No requests matched setup. Got method %s, Path %s, body %s
", r.Method, r.URL.EscapedPath(), requestBody)
}
})
return httptest.NewServer(handlerFunc)
}
Something like this function but it takes a map of request methods and past mapped to appropriate responses and writes them to the writer?
