feat: [CODE-2335]: add dryrun option for rebase API (#2721)

* dryrun rebase

app/api/controller/pullreq/merge.go

@@ -389,7 +389,7 @@ func (c *Controller) Merge(
 		Method:          gitenum.MergeMethod(in.Method),
 	})
 	if err != nil {
-		return nil, nil, fmt.Errorf("merge check execution failed: %w", err)
+		return nil, nil, fmt.Errorf("merge execution failed: %w", err)
 	}
 	//nolint:nestif
 	if mergeOutput.MergeSHA.String() == "" || len(mergeOutput.ConflictFiles) > 0 {

app/api/controller/repo/rebase.go

@@ -34,6 +34,7 @@ type RebaseInput struct {
 	HeadBranch    string  `json:"head_branch"`
 	HeadCommitSHA sha.SHA `json:"head_commit_sha"`
 
+	DryRun      bool `json:"dry_run"`
 	DryRunRules bool `json:"dry_run_rules"`
 	BypassRules bool `json:"bypass_rules"`
 }
@@ -90,11 +91,10 @@ func (c *Controller) Rebase(
 	}
 
 	if in.DryRunRules {
+		// DryRunRules is true: Just return rule violations and don't attempt to rebase.
 		return &types.RebaseResponse{
-			DryRunRulesOutput: types.DryRunRulesOutput{
+			RuleViolations: violations,
-				DryRunRules:    true,
+			DryRunRules:    true,
-				RuleViolations: violations,
-			},
 		}, nil, nil
 	}
 
@@ -125,7 +125,7 @@ func (c *Controller) Rebase(
 
 	if !headBranch.Branch.SHA.Equal(in.HeadCommitSHA) {
 		return nil, nil, usererror.BadRequestf("The commit %s isn't the latest commit on the branch %s",
-			in.HeadCommitSHA, headBranch.Branch.SHA.String())
+			in.HeadCommitSHA, headBranch.Branch.Name)
 	}
 
 	isAncestor, err := c.git.IsAncestor(ctx, git.IsAncestorParams{
@@ -140,9 +140,8 @@ func (c *Controller) Rebase(
 	if isAncestor.Ancestor {
 		// The head branch already contains the latest commit from the base branch - nothing to do.
 		return &types.RebaseResponse{
-			DryRunRulesOutput: types.DryRunRulesOutput{
+			AlreadyAncestor: true,
-				RuleViolations: violations,
+			RuleViolations:  violations,
-			},
 		}, nil, nil
 	}
 
@@ -151,13 +150,20 @@ func (c *Controller) Rebase(
 		return nil, nil, fmt.Errorf("failed to create RPC write params: %w", err)
 	}
 
+	refType := gitenum.RefTypeBranch
+	refName := in.HeadBranch
+	if in.DryRun {
+		refType = gitenum.RefTypeUndefined
+		refName = ""
+	}
+
 	mergeOutput, err := c.git.Merge(ctx, &git.MergeParams{
 		WriteParams:     writeParams,
 		BaseBranch:      in.BaseBranch,
 		HeadRepoUID:     repo.GitUID,
 		HeadBranch:      in.HeadBranch,
-		RefType:         gitenum.RefTypeBranch,
+		RefType:         refType,
-		RefName:         in.HeadBranch,
+		RefName:         refName,
 		HeadExpectedSHA: in.HeadCommitSHA,
 		Method:          gitenum.MergeMethodRebase,
 	})
@@ -165,6 +171,16 @@ func (c *Controller) Rebase(
 		return nil, nil, fmt.Errorf("rebase execution failed: %w", err)
 	}
 
+	if in.DryRun {
+		// DryRun is true: Just return rule violations and list of conflicted files.
+		// No reference is updated, so don't return the resulting commit SHA.
+		return &types.RebaseResponse{
+			RuleViolations: violations,
+			DryRun:         true,
+			ConflictFiles:  mergeOutput.ConflictFiles,
+		}, nil, nil
+	}
+
 	if mergeOutput.MergeSHA.IsEmpty() || len(mergeOutput.ConflictFiles) > 0 {
 		return nil, &types.MergeViolations{
 			ConflictFiles:  mergeOutput.ConflictFiles,
@@ -174,9 +190,7 @@ func (c *Controller) Rebase(
 	}
 
 	return &types.RebaseResponse{
-		DryRunRulesOutput: types.DryRunRulesOutput{
-			RuleViolations: violations,
-		},
 		NewHeadBranchSHA: mergeOutput.MergeSHA,
+		RuleViolations:   violations,
 	}, nil, nil
 }

app/services/usergroup/list_users.go

@@ -16,7 +16,6 @@ package usergroup
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/harness/gitness/app/auth"
 	"github.com/harness/gitness/types"
@@ -27,9 +26,9 @@ func (s *searchService) ListUsers(
 	_ *auth.Session,
 	_ *types.UserGroup,
 ) ([]string, error) {
-	return nil, fmt.Errorf("not implemented")
+	return nil, nil
 }
 
 func (s *searchService) ListUserIDsByGroupIDs(_ context.Context, _ []int64) ([]int64, error) {
-	return nil, fmt.Errorf("not implemented")
+	return nil, nil
 }

git/hook/refupdate.go

@@ -130,6 +130,10 @@ func (u *RefUpdater) Init(ctx context.Context, oldValue, newValue sha.SHA) error
 }
 
 func (u *RefUpdater) InitOld(ctx context.Context, oldValue sha.SHA) error {
+	if u == nil {
+		return nil
+	}
+
 	if u.state != stateInitOld {
 		return fmt.Errorf("invalid operation order: init old requires state=%s, current state=%s",
 			stateInitOld, u.state)
@@ -154,6 +158,10 @@ func (u *RefUpdater) InitOld(ctx context.Context, oldValue sha.SHA) error {
 }
 
 func (u *RefUpdater) InitNew(_ context.Context, newValue sha.SHA) error {
+	if u == nil {
+		return nil
+	}
+
 	if u.state != stateInitNew {
 		return fmt.Errorf("invalid operation order: init new requires state=%s, current state=%s",
 			stateInitNew, u.state)

git/merge.go

@@ -227,7 +227,11 @@ func (s *Service) Merge(ctx context.Context, params *MergeParams) (MergeOutput,
 
 	// handle simple merge check
 
-	if params.RefType == enum.RefTypeUndefined {
+	if params.RefType == enum.RefTypeUndefined && params.Method != enum.MergeMethodRebase {
+		// Merge method rebase can result in conflicts even if other methods do not.
+		// This is because commits are rebased one by one. And this is why for other merge method we just return
+		// list of conflicts, but for rebase we proceed with the rebasing (even if no ref would be updated).
+
 		_, _, conflicts, err := merge.FindConflicts(ctx, repoPath, baseCommitSHA.String(), headCommitSHA.String())
 		if err != nil {
 			return MergeOutput{}, errors.Internal(err,
@@ -281,13 +285,17 @@ func (s *Service) Merge(ctx context.Context, params *MergeParams) (MergeOutput,
 
 	// merge
 
-	refUpdater, err := hook.CreateRefUpdater(s.hookClientFactory, params.EnvVars, repoPath, refPath)
+	var refUpdater *hook.RefUpdater
-	if err != nil {
-		return MergeOutput{}, errors.Internal(err, "failed to create ref updater object")
-	}
 
-	if err := refUpdater.InitOld(ctx, refOldValue); err != nil {
+	if params.RefType != enum.RefTypeUndefined {
-		return MergeOutput{}, errors.Internal(err, "failed to set old reference value for ref updater")
+		refUpdater, err = hook.CreateRefUpdater(s.hookClientFactory, params.EnvVars, repoPath, refPath)
+		if err != nil {
+			return MergeOutput{}, errors.Internal(err, "failed to create ref updater object")
+		}
+
+		if err := refUpdater.InitOld(ctx, refOldValue); err != nil {
+			return MergeOutput{}, errors.Internal(err, "failed to set old reference value for ref updater")
+		}
 	}
 
 	mergeCommitSHA, conflicts, err := mergeFunc(

types/rebase.go

@@ -14,11 +14,14 @@
 
 package types
 
-import (
+import "github.com/harness/gitness/git/sha"
-	"github.com/harness/gitness/git/sha"
-)
 
 type RebaseResponse struct {
-	DryRunRulesOutput
+	AlreadyAncestor  bool             `json:"already_ancestor,omitempty"`
-	NewHeadBranchSHA sha.SHA `json:"new_head_branch_sha"`
+	NewHeadBranchSHA sha.SHA          `json:"new_head_branch_sha"`
+	RuleViolations   []RuleViolations `json:"rule_violations,omitempty"`
+
+	DryRunRules   bool     `json:"dry_run_rules,omitempty"`
+	DryRun        bool     `json:"dry_run,omitempty"`
+	ConflictFiles []string `json:"conflict_files,omitempty"`
 }