Fix incorrect "blob excerpt" link when comparing files (#31013)

When comparing files between the base repo and forked repo, the "blob
excerpt" link should point to the forked repo, because the commit
doesn't exist in base repo.

Co-authored-by: Giteabot <teabot@gitea.io>

templates/repo/diff/section_split.tmpl

@@ -1,4 +1,5 @@
 {{$file := .file}}
+{{$blobExcerptRepoLink := or ctx.RootData.CommitRepoLink ctx.RootData.RepoLink}}
 <colgroup>
 	<col width="50">
 	<col width="10">
@@ -18,17 +19,17 @@
 					<td class="lines-num lines-num-old">
 						<div class="tw-flex">
 						{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 5)}}
-							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=down&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$blobExcerptRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=down&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 								{{svg "octicon-fold-down"}}
 							</button>
 						{{end}}
 						{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 4)}}
-							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=up&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$blobExcerptRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=up&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 								{{svg "octicon-fold-up"}}
 							</button>
 						{{end}}
 						{{if eq $line.GetExpandDirection 2}}
-							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$blobExcerptRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 								{{svg "octicon-fold"}}
 							</button>
 						{{end}}

templates/repo/diff/section_unified.tmpl

@@ -1,4 +1,5 @@
 {{$file := .file}}
+{{$blobExcerptRepoLink := or ctx.RootData.CommitRepoLink ctx.RootData.RepoLink}}
 <colgroup>
 	<col width="50">
 	<col width="50">
@@ -14,17 +15,17 @@
 					<td colspan="2" class="lines-num">
 						<div class="tw-flex">
 							{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 5)}}
-								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=down&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$blobExcerptRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=down&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 									{{svg "octicon-fold-down"}}
 								</button>
 							{{end}}
 							{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 4)}}
-								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=up&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$blobExcerptRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=up&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 									{{svg "octicon-fold-up"}}
 								</button>
 							{{end}}
 							{{if eq $line.GetExpandDirection 2}}
-								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$blobExcerptRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 									{{svg "octicon-fold"}}
 								</button>
 							{{end}}

tests/integration/compare_test.go

@@ -6,9 +6,14 @@ package integration
 import (
 	"fmt"
 	"net/http"
+	"net/url"
 	"strings"
 	"testing"
 
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	repo_service "code.gitea.io/gitea/services/repository"
 	"code.gitea.io/gitea/tests"
 
 	"github.com/stretchr/testify/assert"
@@ -118,3 +123,37 @@ func TestCompareBranches(t *testing.T) {
 
 	inspectCompare(t, htmlDoc, diffCount, diffChanges)
 }
+
+func TestCompareCodeExpand(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		user1 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+		repo, err := repo_service.CreateRepositoryDirectly(db.DefaultContext, user1, user1, repo_service.CreateRepoOptions{
+			Name:          "test_blob_excerpt",
+			Readme:        "Default",
+			AutoInit:      true,
+			DefaultBranch: "main",
+		})
+		assert.NoError(t, err)
+
+		session := loginUser(t, user1.Name)
+		testEditFile(t, session, user1.Name, repo.Name, "main", "README.md", strings.Repeat("a\n", 30))
+
+		user2 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+		session = loginUser(t, user2.Name)
+		testRepoFork(t, session, user1.Name, repo.Name, user2.Name, "test_blob_excerpt-fork")
+		testCreateBranch(t, session, user2.Name, "test_blob_excerpt-fork", "branch/main", "forked-branch", http.StatusSeeOther)
+		testEditFile(t, session, user2.Name, "test_blob_excerpt-fork", "forked-branch", "README.md", strings.Repeat("a\n", 15)+"CHANGED\n"+strings.Repeat("a\n", 15))
+
+		req := NewRequest(t, "GET", "/user1/test_blob_excerpt/compare/main...user2/test_blob_excerpt-fork:forked-branch")
+		resp := session.MakeRequest(t, req, http.StatusOK)
+		htmlDoc := NewHTMLParser(t, resp.Body)
+		els := htmlDoc.Find(`button.code-expander-button[hx-get]`)
+
+		// all the links in the comparison should be to the forked repo&branch
+		assert.NotZero(t, els.Length())
+		for i := 0; i < els.Length(); i++ {
+			link := els.Eq(i).AttrOr("hx-get", "")
+			assert.True(t, strings.HasPrefix(link, "/user2/test_blob_excerpt-fork/blob_excerpt/"))
+		}
+	})
+}