[TESTS] auth LinkAccount test coverage

(cherry picked from commit e11dcc60f2)

use backticks to avoid backslash

(cherry picked from commit 34212791ee)
(cherry picked from commit bde9473c69)
(cherry picked from commit d4deb43084)
(cherry picked from commit 08e91649b0)
(cherry picked from commit 2b988e5415)

[TESTS] auth LinkAccount test coverage (squash)

(cherry picked from commit a2b2e3066b)
(cherry picked from commit 841d1b5073)
(cherry picked from commit 35da630ad8)
(cherry picked from commit caf2dc4fa7)

tests/integration/linkaccount_test.go

@@ -0,0 +1,141 @@
+// SPDX-FileCopyrightText: Copyright the Forgejo contributors
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"context"
+	"net/http"
+	"testing"
+
+	auth_model "code.gitea.io/gitea/models/auth"
+	user_model "code.gitea.io/gitea/models/user"
+	gitea_context "code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/markbates/goth"
+	"github.com/stretchr/testify/assert"
+)
+
+const codebergURL = "https://codeberg.org"
+
+func TestLinkAccountChoose(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+	ctx := context.Background()
+
+	// Create a OIDC source and a known OAuth2 source
+	codebergName := "codeberg"
+	codeberg := addAuthSource(t, authSourcePayloadOIDC(codebergName))
+	gitlabName := "gitlab"
+	gitlab := addAuthSource(t, authSourcePayloadGitLabCustom(gitlabName))
+
+	//
+	// A local user
+	//
+	localUser := &user_model.User{
+		Name:   "linkaccountuser",
+		Email:  "linkaccountuser@example.com",
+		Passwd: "linkaccountuser",
+		Type:   user_model.UserTypeIndividual,
+	}
+	defer createUser(ctx, t, localUser)()
+
+	//
+	// A Codeberg user via OIDC
+	//
+	userCodebergUserID := "1234"
+	userCodeberg := &user_model.User{
+		Name:        "linkaccountcodeberguser",
+		Email:       "linkaccountcodeberguser@example.com",
+		Passwd:      "linkaccountcodeberguser",
+		Type:        user_model.UserTypeIndividual,
+		LoginType:   auth_model.OAuth2,
+		LoginSource: codeberg.ID,
+		LoginName:   userCodebergUserID,
+	}
+	defer createUser(ctx, t, userCodeberg)()
+
+	//
+	// A Gitlab user
+	//
+	userGitLabUserID := "5678"
+	userGitLab := &user_model.User{
+		Name:        "linkaccountgitlabuser",
+		Email:       "linkaccountgitlabuser@example.com",
+		Passwd:      "linkaccountgitlabuser",
+		Type:        user_model.UserTypeIndividual,
+		LoginType:   auth_model.OAuth2,
+		LoginSource: gitlab.ID,
+		LoginName:   userGitLabUserID,
+	}
+	defer createUser(ctx, t, userGitLab)()
+
+	defer func() {
+		testMiddlewareHook = nil
+	}()
+
+	for _, testCase := range []struct {
+		title     string
+		gothUser  goth.User
+		signupTab string
+		signinTab string
+	}{
+		{
+			title: "No existing user",
+			gothUser: goth.User{
+				Provider: codebergName,
+			},
+			signupTab: "item active",
+			signinTab: "item ",
+		},
+		{
+			title: "Matched local user",
+			gothUser: goth.User{
+				Provider: codebergName,
+				Email:    localUser.Email,
+			},
+			signupTab: "item ",
+			signinTab: "item active",
+		},
+		{
+			title: "Matched Codeberg local user",
+			gothUser: goth.User{
+				Provider: codebergName,
+				UserID:   userCodebergUserID,
+				Email:    userCodeberg.Email,
+			},
+			signupTab: "item ",
+			signinTab: "item active",
+		},
+		{
+			title: "Matched GitLab local user",
+			gothUser: goth.User{
+				Provider: gitlabName,
+				UserID:   userGitLabUserID,
+				Email:    userGitLab.Email,
+			},
+			signupTab: "item ",
+			signinTab: "item active",
+		},
+	} {
+		t.Run(testCase.title, func(t *testing.T) {
+			testMiddlewareHook = func(ctx *gitea_context.Context) {
+				ctx.Session.Set("linkAccountGothUser", testCase.gothUser)
+			}
+
+			req := NewRequest(t, "GET", "/user/link_account")
+			resp := MakeRequest(t, req, http.StatusOK)
+			if assert.Equal(t, resp.Code, http.StatusOK, resp.Body) {
+				doc := NewHTMLParser(t, resp.Body)
+
+				class, exists := doc.Find(`.new-menu-inner .item[data-tab="auth-link-signup-tab"]`).Attr("class")
+				assert.True(t, exists, resp.Body)
+				assert.Equal(t, testCase.signupTab, class)
+
+				class, exists = doc.Find(`.new-menu-inner .item[data-tab="auth-link-signin-tab"]`).Attr("class")
+				assert.True(t, exists)
+				assert.Equal(t, testCase.signinTab, class)
+			}
+		})
+	}
+}