Fix MR Selection, Go Code Refactor (#358)

refactor: Refactors the Go codebase into a more modular and idiomatic approach
fix: require selection of specific MR when there are multiple targets for a given source branch
feat: Allows for the passing of Gitlab's filter options when choosing an MR, improves MR selection
feat: API to choose an MR from a list based on the provided username's involvement as an assignee/reviewer/author

This is a #MINOR release

cmd/app/job_test.go

@@ -0,0 +1,71 @@
+package app
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/xanzy/go-gitlab"
+)
+
+type fakeTraceFileGetter struct {
+	testBase
+}
+
+func getTraceFileData(t *testing.T, svc ServiceWithHandler, request *http.Request) JobTraceResponse {
+	res := httptest.NewRecorder()
+	svc.handler(res, request)
+
+	var data JobTraceResponse
+	err := json.Unmarshal(res.Body.Bytes(), &data)
+	if err != nil {
+		t.Error(err)
+	}
+	return data
+}
+
+func (f fakeTraceFileGetter) GetTraceFile(pid interface{}, jobID int, options ...gitlab.RequestOptionFunc) (*bytes.Reader, *gitlab.Response, error) {
+	resp, err := f.handleGitlabError()
+	if err != nil {
+		return nil, nil, err
+	}
+	re := bytes.NewReader([]byte("Some data"))
+	return re, resp, err
+}
+
+// var jobId = 0
+func TestJobHandler(t *testing.T) {
+	t.Run("Should read a job trace file", func(t *testing.T) {
+		request := makeRequest(t, http.MethodGet, "/job", JobTraceRequest{})
+		client := fakeTraceFileGetter{}
+		svc := traceFileService{testProjectData, client}
+		data := getTraceFileData(t, svc, request)
+		assert(t, data.Message, "Log file read")
+		assert(t, data.Status, http.StatusOK)
+		assert(t, data.File, "Some data")
+	})
+	t.Run("Disallows non-GET methods", func(t *testing.T) {
+		request := makeRequest(t, http.MethodPost, "/job", JobTraceRequest{})
+		client := fakeTraceFileGetter{}
+		svc := traceFileService{testProjectData, client}
+		data := getFailData(t, svc, request)
+		checkBadMethod(t, data, http.MethodGet)
+	})
+	t.Run("Handles errors from Gitlab client", func(t *testing.T) {
+		request := makeRequest(t, http.MethodGet, "/job", JobTraceRequest{})
+		client := fakeTraceFileGetter{testBase{errFromGitlab: true}}
+		svc := traceFileService{testProjectData, client}
+		data := getFailData(t, svc, request)
+		checkErrorFromGitlab(t, data, "Could not get trace file for job")
+	})
+
+	t.Run("Handles non-200s from Gitlab client", func(t *testing.T) {
+		request := makeRequest(t, http.MethodGet, "/job", JobTraceRequest{})
+		client := fakeTraceFileGetter{testBase{status: http.StatusSeeOther}}
+		svc := traceFileService{testProjectData, client}
+		data := getFailData(t, svc, request)
+		checkNon200(t, data, "Could not get trace file for job", "/job")
+	})
+}