github: add function for retrieving repository info (#768)

backend/mock/service/githubmock/githubmock.go

@@ -47,6 +47,10 @@ func (s svc) GetCommit(ctx context.Context, ref *github.RemoteRef) (*github.Comm
 	panic("implement me")
 }
 
+func (s svc) GetRepository(ctx context.Context, ref *github.RemoteRef) (*github.Repository, error) {
+	panic("implement me")
+}
+
 func NewAsService(*any.Any, *zap.Logger, tally.Scope) (service.Service, error) {
 	return New(), nil
 }

backend/service/github/github.go

@@ -56,6 +56,13 @@ type RemoteRef struct {
 	Ref string
 }
 
+// Repository contains information about a requested repository.
+type Repository struct {
+	Name          string
+	Owner         string
+	DefaultBranch string
+}
+
 // File contains information about a requested file, including its content.
 type File struct {
 	Path             string
@@ -74,6 +81,7 @@ type Client interface {
 	CreateIssueComment(ctx context.Context, ref *RemoteRef, number int, body string) error
 	CompareCommits(ctx context.Context, ref *RemoteRef, compareSHA string) (*scgithubv1.CommitComparison, error)
 	GetCommit(ctx context.Context, ref *RemoteRef) (*Commit, error)
+	GetRepository(ctx context.Context, ref *RemoteRef) (*Repository, error)
 }
 
 // This func can be used to create comments for PRs or Issues
@@ -306,3 +314,24 @@ func (s *svc) GetCommit(ctx context.Context, ref *RemoteRef) (*Commit, error) {
 		Files: commit.Files,
 	}, nil
 }
+
+func (s *svc) GetRepository(ctx context.Context, repo *RemoteRef) (*Repository, error) {
+	q := &getRepositoryQuery{}
+	params := map[string]interface{}{
+		"owner": githubv4.String(repo.RepoOwner),
+		"name":  githubv4.String(repo.RepoName),
+	}
+
+	err := s.graphQL.Query(ctx, q, params)
+	if err != nil {
+		return nil, err
+	}
+
+	r := &Repository{
+		Name:          repo.RepoName,
+		Owner:         repo.RepoOwner,
+		DefaultBranch: string(q.Repository.DefaultBranchRef.Name),
+	}
+
+	return r, nil
+}

backend/service/github/github_test.go

@@ -350,3 +350,64 @@ func TestGetCommit(t *testing.T) {
 		})
 	}
 }
+
+type getRepositoryMock struct {
+	v4client
+	branchName string
+}
+
+func (g *getRepositoryMock) Query(ctx context.Context, query interface{}, variables map[string]interface{}) error {
+	q, ok := query.(*getRepositoryQuery)
+	if !ok {
+		panic("not a query")
+	}
+	q.Repository.DefaultBranchRef.Name = g.branchName
+	return nil
+}
+
+var getDefaultBranchTests = []struct {
+	name string
+	v4   getRepositoryMock
+
+	wantDefaultBranch string
+}{
+	{
+		name:              "1. default repo with main branch",
+		v4:                getRepositoryMock{branchName: "main"},
+		wantDefaultBranch: "main",
+	},
+	{
+		name:              "2. default repo with master branch",
+		v4:                getRepositoryMock{branchName: "master"},
+		wantDefaultBranch: "master",
+	},
+}
+
+func TestGetRepository(t *testing.T) {
+	t.Parallel()
+	for _, tt := range getDefaultBranchTests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			a := assert.New(t)
+			s := &svc{graphQL: &tt.v4}
+
+			repo, err := s.GetRepository(context.Background(),
+				&RemoteRef{
+					RepoOwner: "owner",
+					RepoName:  "myRepo",
+				},
+			)
+
+			if err != nil {
+				a.FailNowf("unexpected error: %s", err.Error())
+				return
+			}
+
+			gotDefaultBranch := repo.DefaultBranch
+
+			a.Equal(gotDefaultBranch, tt.wantDefaultBranch)
+			a.Nil(err)
+		})
+	}
+}

backend/service/github/graphql.go

@@ -36,3 +36,11 @@ type getFileQuery struct {
 		} `graphql:"object(expression:$refPath)"`
 	} `graphql:"repository(owner:$owner,name:$name)"`
 }
+
+type getRepositoryQuery struct {
+	Repository struct {
+		DefaultBranchRef struct {
+			Name string
+		}
+	} `graphql:"repository(owner:$owner,name:$name)"`
+}