feat(pulls): add pull lookup by base and head

Co-Authored-By: Virgil <virgil@lethean.io>

pulls.go

@@ -68,6 +68,21 @@ func (s *PullService) IterFiles(ctx context.Context, owner, repo string, index i
 	return ListIter[types.ChangedFile](ctx, s.client, path, nil)
 }
 
+// GetByBaseHead returns a pull request for a given base and head branch pair.
+func (s *PullService) GetByBaseHead(ctx context.Context, owner, repo, base, head string) (*types.PullRequest, error) {
+	path := ResolvePath("/api/v1/repos/{owner}/{repo}/pulls/{base}/{head}", pathParams(
+		"owner", owner,
+		"repo", repo,
+		"base", base,
+		"head", head,
+	))
+	var out types.PullRequest
+	if err := s.client.Get(ctx, path, &out); err != nil {
+		return nil, err
+	}
+	return &out, nil
+}
+
 // ListReviewers returns all users who can be requested to review a pull request.
 func (s *PullService) ListReviewers(ctx context.Context, owner, repo string) ([]types.User, error) {
 	path := ResolvePath("/api/v1/repos/{owner}/{repo}/reviewers", pathParams("owner", owner, "repo", repo))

pulls_test.go

@@ -151,6 +151,30 @@ func TestPullService_ListFiles_Good(t *testing.T) {
 	}
 }
 
+func TestPullService_GetByBaseHead_Good(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			t.Errorf("expected GET, got %s", r.Method)
+		}
+		if r.URL.Path != "/api/v1/repos/core/go-forge/pulls/main/feature" {
+			t.Errorf("wrong path: %s", r.URL.Path)
+			http.NotFound(w, r)
+			return
+		}
+		json.NewEncoder(w).Encode(types.PullRequest{Index: 7, Title: "Add feature"})
+	}))
+	defer srv.Close()
+
+	f := NewForge(srv.URL, "tok")
+	pr, err := f.Pulls.GetByBaseHead(context.Background(), "core", "go-forge", "main", "feature")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if pr.Index != 7 || pr.Title != "Add feature" {
+		t.Fatalf("got %+v", pr)
+	}
+}
+
 func TestPullService_IterFiles_Good(t *testing.T) {
 	requests := 0
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {