pkg/gui: Allow user to select remote and branch when creating a PR

When creating a PR against a selected branch (via O = "create pull request
options"), the user will first be asked to select a remote (if there is more
than one). After that, the suggestion area is populated with all remote branches
at that origin - instead of all local ones. After all, creating a PR against a
branch that doesn't exist on the remote won't work.

Please note that the "PR is not filed against 'origin' remote" use cases (e.g. when
contributing via a fork that is 'origin' to a GitHub project that is
'upstream'), is not working correctly yet.

Fixes #1826.

pkg/gui/controllers/branches_controller.go

@@ -730,11 +730,23 @@ func (self *BranchesController) createPullRequestMenu(selectedBranch *models.Bra
 			{
 				LabelColumns: fromToLabelColumns(branch.Name, self.c.Tr.SelectBranch),
 				OnPress: func() error {
+					if !branch.IsTrackingRemote() {
+						return errors.New(self.c.Tr.PullRequestNoUpstream)
+					}
+
+					if len(self.c.Model().Remotes) == 1 {
+						toRemote := self.c.Model().Remotes[0].Name
+						self.c.Log.Debugf("PR will target the only existing remote '%s'", toRemote)
+						return self.promptForTargetBranchNameAndCreatePullRequest(branch, toRemote)
+					}
+
 					self.c.Prompt(types.PromptOpts{
-						Title:               branch.Name + " →",
-						FindSuggestionsFunc: self.c.Helpers().Suggestions.GetRemoteBranchesSuggestionsFunc("/"),
-						HandleConfirm: func(targetBranchName string) error {
-							return self.createPullRequest(branch.Name, targetBranchName)
+						Title:               self.c.Tr.SelectTargetRemote,
+						FindSuggestionsFunc: self.c.Helpers().Suggestions.GetRemoteSuggestionsFunc(),
+						HandleConfirm: func(toRemote string) error {
+							self.c.Log.Debugf("PR will target remote '%s'", toRemote)
+
+							return self.promptForTargetBranchNameAndCreatePullRequest(branch, toRemote)
 						},
 					})
 
@@ -764,6 +776,26 @@ func (self *BranchesController) createPullRequestMenu(selectedBranch *models.Bra
 	return self.c.Menu(types.CreateMenuOptions{Title: fmt.Sprint(self.c.Tr.CreatePullRequestOptions), Items: menuItems})
 }
 
+func (self *BranchesController) promptForTargetBranchNameAndCreatePullRequest(fromBranch *models.Branch, toRemote string) error {
+	remoteDoesNotExist := lo.NoneBy(self.c.Model().Remotes, func(remote *models.Remote) bool {
+		return remote.Name == toRemote
+	})
+	if remoteDoesNotExist {
+		return fmt.Errorf(self.c.Tr.NoValidRemoteName, toRemote)
+	}
+
+	self.c.Prompt(types.PromptOpts{
+		Title:               fmt.Sprintf("%s → %s/", fromBranch.UpstreamBranch, toRemote),
+		FindSuggestionsFunc: self.c.Helpers().Suggestions.GetRemoteBranchesForRemoteSuggestionsFunc(toRemote),
+		HandleConfirm: func(toBranch string) error {
+			self.c.Log.Debugf("PR will target branch '%s' on remote '%s'", toBranch, toRemote)
+			return self.createPullRequest(fromBranch.UpstreamBranch, toBranch)
+		},
+	})
+
+	return nil
+}
+
 func (self *BranchesController) createPullRequest(from string, to string) error {
 	url, err := self.c.Helpers().Host.GetPullRequestURL(from, to)
 	if err != nil {

pkg/gui/controllers/helpers/suggestions_helper.go

@@ -162,10 +162,26 @@ func (self *SuggestionsHelper) getRemoteBranchNames(separator string) []string {
 	})
 }
 
+func (self *SuggestionsHelper) getRemoteBranchNamesForRemote(remoteName string) []string {
+	remote, ok := lo.Find(self.c.Model().Remotes, func(remote *models.Remote) bool {
+		return remote.Name == remoteName
+	})
+	if ok {
+		return lo.Map(remote.Branches, func(branch *models.RemoteBranch, _ int) string {
+			return branch.Name
+		})
+	}
+	return nil
+}
+
 func (self *SuggestionsHelper) GetRemoteBranchesSuggestionsFunc(separator string) func(string) []*types.Suggestion {
 	return FilterFunc(self.getRemoteBranchNames(separator), self.c.UserConfig().Gui.UseFuzzySearch())
 }
 
+func (self *SuggestionsHelper) GetRemoteBranchesForRemoteSuggestionsFunc(remoteName string) func(string) []*types.Suggestion {
+	return FilterFunc(self.getRemoteBranchNamesForRemote(remoteName), self.c.UserConfig().Gui.UseFuzzySearch())
+}
+
 func (self *SuggestionsHelper) getTagNames() []string {
 	return lo.Map(self.c.Model().Tags, func(tag *models.Tag, _ int) string {
 		return tag.Name

pkg/i18n/english.go

@@ -686,6 +686,8 @@ type TranslationSet struct {
 	CreatePullRequestOptions                 string
 	DefaultBranch                            string
 	SelectBranch                             string
+	SelectTargetRemote                       string
+	NoValidRemoteName                        string
 	CreatePullRequest                        string
 	SelectConfigFile                         string
 	NoConfigFileFoundErr                     string
@@ -1676,6 +1678,8 @@ func EnglishTranslationSet() *TranslationSet {
 		CreatePullRequestOptions:                 "View create pull request options",
 		DefaultBranch:                            "Default branch",
 		SelectBranch:                             "Select branch",
+		SelectTargetRemote:                       "Select target remote",
+		NoValidRemoteName:                        "A remote named '%s' does not exist",
 		SelectConfigFile:                         "Select config file",
 		NoConfigFileFoundErr:                     "No config file found",
 		LoadingFileSuggestions:                   "Loading file suggestions",

pkg/integration/tests/branch/open_pull_request_invalid_target_remote_name.go

@@ -0,0 +1,54 @@
+package branch
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var OpenPullRequestInvalidTargetRemoteName = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Open up a pull request, specifying a non-existing target remote",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		// Create an initial commit ('git branch set-upstream-to' bails out otherwise)
+		shell.CreateFileAndAdd("file", "content1")
+		shell.Commit("one")
+
+		// Create a new branch
+		shell.NewBranch("branch-1")
+
+		// Create a couple of remotes
+		shell.CloneIntoRemote("upstream")
+		shell.CloneIntoRemote("origin")
+
+		// To allow a pull request to be created from a branch, it must have an upstream set.
+		shell.SetBranchUpstream("branch-1", "origin/branch-1")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		// Open a PR for the current branch (i.e. 'branch-1')
+		t.Views().
+			Branches().
+			Focus().
+			Press(keys.Branches.ViewPullRequestOptions)
+
+		t.ExpectPopup().
+			Menu().
+			Title(Equals("View create pull request options")).
+			Select(Contains("Select branch")).
+			Confirm()
+
+		// Verify that we're prompted to enter the remote and enter the name of a non-existing one.
+		t.ExpectPopup().
+			Prompt().
+			Title(Equals("Select target remote")).
+			Type("non-existing-remote").
+			Confirm()
+
+		// Verify that this leads to an error being shown (instead of progressing to branch selection).
+		t.ExpectPopup().Alert().
+			Title(Equals("Error")).
+			Content(Contains("A remote named 'non-existing-remote' does not exist")).
+			Confirm()
+	},
+})

pkg/integration/tests/branch/open_pull_request_select_remote_and_target_branch.go

@@ -0,0 +1,70 @@
+package branch
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var OpenPullRequestSelectRemoteAndTargetBranch = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Open up a pull request, specifying a remote and target branch",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig: func(config *config.AppConfig) {
+		config.GetUserConfig().OS.OpenLink = "echo {{link}} > /tmp/openlink"
+	},
+	SetupRepo: func(shell *Shell) {
+		// Create an initial commit ('git branch set-upstream-to' bails out otherwise)
+		shell.CreateFileAndAdd("file", "content1")
+		shell.Commit("one")
+
+		// Create a new branch and a remote that has that branch
+		shell.NewBranch("branch-1")
+		shell.CloneIntoRemote("upstream")
+
+		// Create another branch and a second remote. The first remote doesn't have this branch.
+		shell.NewBranch("branch-2")
+		shell.CloneIntoRemote("origin")
+
+		// To allow a pull request to be created from a branch, it must have an upstream set.
+		shell.SetBranchUpstream("branch-2", "origin/branch-2")
+
+		shell.RunCommand([]string{"git", "remote", "set-url", "origin", "https://github.com/my-personal-fork/lazygit"})
+		shell.RunCommand([]string{"git", "remote", "set-url", "upstream", "https://github.com/jesseduffield/lazygit"})
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		// Open a PR for the current branch (i.e. 'branch-2')
+		t.Views().
+			Branches().
+			Focus().
+			Press(keys.Branches.ViewPullRequestOptions)
+
+		t.ExpectPopup().
+			Menu().
+			Title(Equals("View create pull request options")).
+			Select(Contains("Select branch")).
+			Confirm()
+
+		// Verify that we're prompted to enter the remote
+		t.ExpectPopup().
+			Prompt().
+			Title(Equals("Select target remote")).
+			SuggestionLines(
+				Equals("origin"),
+				Equals("upstream")).
+			ConfirmSuggestion(Equals("upstream"))
+
+		// Verify that we're prompted to enter the target branch and that only those branches
+		// present in the selected remote are listed as suggestions (i.e. 'branch-2' is not there).
+		t.ExpectPopup().
+			Prompt().
+			Title(Equals("branch-2 → upstream/")).
+			SuggestionLines(
+				Equals("branch-1"),
+				Equals("master")).
+			ConfirmSuggestion(Equals("master"))
+
+		// Verify that the expected URL is used (by checking the openlink file)
+		// TODO: How exactly to best do that?
+		t.Shell().RunCommand([]string{"cat", "/tmp/openlink"})
+	},
+})

pkg/integration/tests/test_list.go

@@ -48,7 +48,9 @@ var tests = []*components.IntegrationTest{
 	branch.NewBranchAutostash,
 	branch.NewBranchFromRemoteTrackingDifferentName,
 	branch.NewBranchFromRemoteTrackingSameName,
+	branch.OpenPullRequestInvalidTargetRemoteName,
 	branch.OpenPullRequestNoUpstream,
+	branch.OpenPullRequestSelectRemoteAndTargetBranch,
 	branch.OpenWithCliArg,
 	branch.Rebase,
 	branch.RebaseAbortOnConflict,