Fix the Fork button in repo headers

In #2445, I lifted out the fork button into its own template, but did
not update it properly. This resulted in the fork button's counter not
displaying, and pointing to the wrong place too.

This patch updates the template to account for it moving to a separate
file, and also adds test cases to verify the button is display as it
should be.

Fixes #2494.

Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>

templates/repo/header_fork.tmpl

@@ -1,3 +1,4 @@
+{{with .Repository}}
 {{if and (not .IsEmpty) ($.Permission.CanRead $.UnitTypeCode)}}
 	<div class="ui labeled button
 		{{if or (not $.IsSigned) (and (not $.CanSignedUserFork) (not $.UserAndOrgForks))}}
@@ -48,3 +49,4 @@
 		</a>
 	</div>
 {{end}}
+{{end}}

tests/integration/repo_fork_test.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
+	"strings"
 	"testing"
 
 	"code.gitea.io/gitea/models/db"
@@ -124,6 +125,44 @@ func TestRepoFork(t *testing.T) {
 			})
 		})
 
+		t.Run("fork button", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, "GET", "/user2/repo1/issues")
+			resp := MakeRequest(t, req, http.StatusOK)
+			htmlDoc := NewHTMLParser(t, resp.Body)
+
+			forkButton := htmlDoc.Find("a[href*='/forks']")
+			assert.EqualValues(t, 1, forkButton.Length())
+
+			href, _ := forkButton.Attr("href")
+			assert.Equal(t, "/user2/repo1/forks", href)
+			assert.Equal(t, "0", strings.TrimSpace(forkButton.Text()))
+
+			t.Run("no fork button on empty repo", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+
+				// Create an empty repository
+				repo, err := repo_service.CreateRepository(db.DefaultContext, user5, user5, repo_service.CreateRepoOptions{
+					Name:     "empty-repo",
+					AutoInit: false,
+				})
+				defer func() {
+					repo_service.DeleteRepository(db.DefaultContext, user5, repo, false)
+				}()
+				assert.NoError(t, err)
+				assert.NotEmpty(t, repo)
+
+				// Load the repository home view
+				req := NewRequest(t, "GET", repo.HTMLURL())
+				resp := session.MakeRequest(t, req, http.StatusOK)
+				htmlDoc := NewHTMLParser(t, resp.Body)
+
+				// On an empty repo, the fork button is not present
+				htmlDoc.AssertElement(t, ".basic.button[href*='/fork']", false)
+			})
+		})
+
 		t.Run("DISABLE_FORKS", func(t *testing.T) {
 			defer test.MockVariableValue(&setting.Repository.DisableForks, true)()
 			defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()