Generate Diff and Patch direct from Pull head (#10936) (#10938)

Backport #10936

* Generate Diff and Patch direct from Pull head

Fix #10932
Also fix "Empty Diff/Patch File when pull is merged"

Closes #10934

* Add tests to ensure that diff does not change
* Ensure diffs and pulls pages work if head branch is deleted too

Signed-off-by: Andrew Thornton <art27@cantab.net>

2 files changed, 72 insertions, 22 deletions

diff --git a/integrations/git_test.go b/integrations/git_test.go
index 8e02bc4db9..8813f34be7 100644
--- a/integrations/git_test.go
+++ b/integrations/git_test.go
@@ -71,7 +71,6 @@ func testGit(t *testing.T, u *url.URL) {
 		t.Run("BranchProtectMerge", doBranchProtectPRMerge(&httpContext, dstPath))
 		t.Run("MergeFork", func(t *testing.T) {
 			t.Run("CreatePRAndMerge", doMergeFork(httpContext, forkedUserCtx, "master", httpContext.Username+":master"))
-			t.Run("DeleteRepository", doAPIDeleteRepository(httpContext))
 			rawTest(t, &forkedUserCtx, little, big, littleLFS, bigLFS)
 			mediaTest(t, &forkedUserCtx, little, big, littleLFS, bigLFS)
 		})
@@ -111,7 +110,6 @@ func testGit(t *testing.T, u *url.URL) {
 			t.Run("BranchProtectMerge", doBranchProtectPRMerge(&sshContext, dstPath))
 			t.Run("MergeFork", func(t *testing.T) {
 				t.Run("CreatePRAndMerge", doMergeFork(sshContext, forkedUserCtx, "master", sshContext.Username+":master"))
-				t.Run("DeleteRepository", doAPIDeleteRepository(sshContext))
 				rawTest(t, &forkedUserCtx, little, big, littleLFS, bigLFS)
 				mediaTest(t, &forkedUserCtx, little, big, littleLFS, bigLFS)
 			})
@@ -419,8 +417,62 @@ func doMergeFork(ctx, baseCtx APITestContext, baseBranch, headBranch string) fun
 			pr, err = doAPICreatePullRequest(ctx, baseCtx.Username, baseCtx.Reponame, baseBranch, headBranch)(t)
 			assert.NoError(t, err)
 		})
+		t.Run("EnsureCanSeePull", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+			req = NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d/files", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+			req = NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d/commits", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+		})
+		var diffStr string
+		t.Run("GetDiff", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d.diff", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			resp := ctx.Session.MakeRequest(t, req, http.StatusOK)
+			diffStr = resp.Body.String()
+		})
 		t.Run("MergePR", doAPIMergePullRequest(baseCtx, baseCtx.Username, baseCtx.Reponame, pr.Index))
-
+		t.Run("EnsureCanSeePull", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+			req = NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d/files", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+			req = NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d/commits", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+		})
+		t.Run("EnsureDiffNoChange", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d.diff", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			resp := ctx.Session.MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, diffStr, resp.Body.String())
+		})
+		t.Run("DeleteHeadBranch", doBranchDelete(baseCtx, baseCtx.Username, baseCtx.Reponame, headBranch))
+		t.Run("EnsureCanSeePull", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+			req = NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d/files", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+			req = NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d/commits", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+		})
+		t.Run("EnsureDiffNoChange", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d.diff", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			resp := ctx.Session.MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, diffStr, resp.Body.String())
+		})
+		t.Run("DeleteRepository", doAPIDeleteRepository(ctx))
+		t.Run("EnsureCanSeePull", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+			req = NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d/files", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+			req = NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d/commits", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			ctx.Session.MakeRequest(t, req, http.StatusOK)
+		})
+		t.Run("EnsureDiffNoChange", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s/%s/pulls/%d.diff", url.PathEscape(baseCtx.Username), url.PathEscape(baseCtx.Reponame), pr.Index))
+			resp := ctx.Session.MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, diffStr, resp.Body.String())
+		})
 	}
 }
 
@@ -493,3 +545,14 @@ func doPushCreate(ctx APITestContext, u *url.URL) func(t *testing.T) {
 		assert.True(t, repo.IsPrivate)
 	}
 }
+
+func doBranchDelete(ctx APITestContext, owner, repo, branch string) func(*testing.T) {
+	return func(t *testing.T) {
+		csrf := GetCSRF(t, ctx.Session, fmt.Sprintf("/%s/%s/branches", url.PathEscape(owner), url.PathEscape(repo)))
+
+		req := NewRequestWithValues(t, "POST", fmt.Sprintf("/%s/%s/branches/delete?name=%s", url.PathEscape(owner), url.PathEscape(repo), url.QueryEscape(branch)), map[string]string{
+			"_csrf": csrf,
+		})
+		ctx.Session.MakeRequest(t, req, http.StatusOK)
+	}
+}
diff --git a/services/pull/patch.go b/services/pull/patch.go
index 57a2997b36..295d889248 100644
--- a/services/pull/patch.go
+++ b/services/pull/patch.go
@@ -31,32 +31,19 @@ func DownloadPatch(pr *models.PullRequest, w io.Writer, patch bool) error {
 
 // DownloadDiffOrPatch will write the patch for the pr to the writer
 func DownloadDiffOrPatch(pr *models.PullRequest, w io.Writer, patch bool) error {
-	// Clone base repo.
-	tmpBasePath, err := createTemporaryRepo(pr)
-	if err != nil {
-		log.Error("CreateTemporaryPath: %v", err)
+	if err := pr.LoadBaseRepo(); err != nil {
+		log.Error("Unable to load base repository ID %d for pr #%d [%d]", pr.BaseRepoID, pr.Index, pr.ID)
 		return err
 	}
-	defer func() {
-		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
-			log.Error("DownloadDiff: RemoveTemporaryPath: %s", err)
-		}
-	}()
 
-	gitRepo, err := git.OpenRepository(tmpBasePath)
+	gitRepo, err := git.OpenRepository(pr.BaseRepo.RepoPath())
 	if err != nil {
 		return fmt.Errorf("OpenRepository: %v", err)
 	}
 	defer gitRepo.Close()
-
-	pr.MergeBase, err = git.NewCommand("merge-base", "--", "base", "tracking").RunInDir(tmpBasePath)
-	if err != nil {
-		pr.MergeBase = "base"
-	}
-	pr.MergeBase = strings.TrimSpace(pr.MergeBase)
-	if err := gitRepo.GetDiffOrPatch(pr.MergeBase, "tracking", w, patch); err != nil {
-		log.Error("Unable to get patch file from %s to %s in %s/%s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.MustOwner().Name, pr.BaseRepo.Name, err)
-		return fmt.Errorf("Unable to get patch file from %s to %s in %s/%s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.MustOwner().Name, pr.BaseRepo.Name, err)
+	if err := gitRepo.GetDiffOrPatch(pr.MergeBase, pr.GetGitRefName(), w, patch); err != nil {
+		log.Error("Unable to get patch file from %s to %s in %s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.FullName(), err)
+		return fmt.Errorf("Unable to get patch file from %s to %s in %s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.FullName(), err)
 	}
 	return nil
 }