test: add e2e tests with local Forgejo instance (#201)

* feat(forge): add new forge for forgejo

We only support repositories hosted on Forgejo instances, but not
Forgejo Actions or Woodpecker as CI solutions for now.

* test(e2e): introduce e2e test framework with local forgejo

test/e2e/framework.go

@@ -0,0 +1,96 @@
+package e2e
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"encoding/hex"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/apricote/releaser-pleaser/cmd/rp/cmd"
+)
+
+const (
+	TestDefaultBranch = "main"
+)
+
+func randomString() string {
+	randomBytes := make([]byte, 4)
+	if _, err := rand.Read(randomBytes); err != nil {
+		panic(err)
+	}
+	return hex.EncodeToString(randomBytes)
+}
+
+type Framework struct {
+	runID string
+	forge TestForge
+}
+
+func NewFramework(ctx context.Context, forge TestForge) (*Framework, error) {
+	f := &Framework{
+		runID: randomString(),
+		forge: forge,
+	}
+
+	err := forge.Init(ctx, f.runID)
+	if err != nil {
+		return nil, err
+	}
+
+	return f, nil
+}
+
+type Repository struct {
+	Name string
+}
+
+func (f *Framework) NewRepository(t *testing.T, name string) *Repository {
+	t.Helper()
+
+	r := &Repository{
+		Name: fmt.Sprintf("%s-%s-%s", name, f.runID, randomString()),
+	}
+
+	repo, err := f.forge.CreateRepo(t, CreateRepoOpts{
+		Name:          r.Name,
+		Description:   name,
+		DefaultBranch: TestDefaultBranch,
+	})
+	require.NoError(t, err)
+	require.NotNil(t, repo)
+
+	return r
+}
+
+func (f *Framework) Run(t *testing.T, r *Repository, extraFiles []string) error {
+	t.Helper()
+
+	ctx := t.Context()
+
+	rootCmd := cmd.NewRootCmd()
+	rootCmd.SetArgs(append([]string{
+		"run",
+		fmt.Sprintf("--repo=%s", r.Name),
+		fmt.Sprintf("--extra-files=%q", strings.Join(extraFiles, "\n")),
+	}, f.forge.RunArguments()...))
+
+	var stdout, stderr bytes.Buffer
+
+	rootCmd.SetOut(&stdout)
+	rootCmd.SetErr(&stderr)
+
+	err := rootCmd.ExecuteContext(ctx)
+
+	stdoutString := stdout.String()
+	stderrString := stderr.String()
+
+	t.Log(stdoutString)
+	t.Log(stderrString)
+
+	return err
+}