Add tests demonstrating that we ignore the conflict-marker-size gitattribute

When a file's conflict markers aren't seven characters long we don't
recognize them at all. Two things go wrong: we consider the file's
conflicts resolved, so we stage it and offer to continue the merge a
moment after stopping at it; and pressing enter on it shows its diff
instead of the merge conflicts view, leaving no way to resolve it in
lazygit.

pkg/integration/tests/conflicts/conflict_marker_size_not_auto_staged.go

@@ -0,0 +1,49 @@
+package conflicts
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+	"github.com/jesseduffield/lazygit/pkg/integration/tests/shared"
+)
+
+var ConflictMarkerSizeNotAutoStaged = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Doesn't auto-stage an unresolved file whose conflict-marker-size gitattribute makes its markers longer than usual",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shared.SetCustomConflictMarkerSize(shell)
+		shared.CreateMergeConflictFile(shell)
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Common().PretendMergeOrRebaseStartedInLazygit()
+
+		t.Views().Files().
+			IsFocused().
+			Lines(
+				Contains("UU file").IsSelected(),
+			).
+			// Each refresh checks whether the conflicts are still there
+			Press(keys.Universal.Refresh).
+			/* EXPECTED:
+			// They are, so the file doesn't get staged and we don't get asked to
+			// continue the merge
+			Lines(
+				Contains("UU file").IsSelected(),
+			).
+			// Once they really are resolved, we do
+			Tap(func() {
+				t.Shell().UpdateFile("file", "resolved content")
+			}).
+			Press(keys.Universal.Refresh).
+			Tap(func() {
+				t.Common().ContinueOnConflictsResolved("merge")
+			}).
+			IsEmpty()
+			ACTUAL: */
+			Tap(func() {
+				t.Common().ContinueOnConflictsResolved("merge")
+			}).
+			IsEmpty()
+	},
+})

pkg/integration/tests/conflicts/conflict_marker_size_resolve.go

@@ -0,0 +1,45 @@
+package conflicts
+
+import (
+	"strings"
+
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+	"github.com/jesseduffield/lazygit/pkg/integration/tests/shared"
+)
+
+var ConflictMarkerSizeResolve = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Resolves a conflict in a file whose conflict-marker-size gitattribute makes its markers longer than usual",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shared.SetCustomConflictMarkerSize(shell)
+		shared.CreateMergeConflictFileMultiple(shell)
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		startMarker := strings.Repeat("<", shared.CustomConflictMarkerSize)
+
+		t.Views().Files().
+			IsFocused().
+			Lines(
+				Contains("UU file").IsSelected(),
+			).
+			PressEnter()
+
+		/* EXPECTED:
+		t.Views().MergeConflicts().
+			IsFocused().
+			SelectedLines(
+				Contains(startMarker+" HEAD"),
+				Contains("First Change"),
+				Contains(strings.Repeat("=", shared.CustomConflictMarkerSize)),
+			).
+			PressPrimaryAction().
+			Content(DoesNotContain(startMarker + " HEAD\nFirst Change"))
+		ACTUAL: */
+		// We don't recognize the markers, so instead of the merge conflicts view
+		// we get the file's diff
+		t.Views().Main().Content(Contains(startMarker + " HEAD"))
+	},
+})

pkg/integration/tests/shared/conflicts.go

@@ -1,6 +1,8 @@
 package shared
 
 import (
+	"fmt"
+
 	. "github.com/jesseduffield/lazygit/pkg/integration/components"
 )
 
@@ -28,6 +30,20 @@ Second Change
 File
 `
 
+// A conflict-marker-size that isn't git's default of 7. It's set for file types
+// whose regular content tends to contain marker-looking lines, e.g.
+// documentation about merging, or test scripts.
+const CustomConflictMarkerSize = 32
+
+// Makes git write conflict markers of CustomConflictMarkerSize characters into
+// the file that the setups below create conflicts in. Call this before one of
+// them.
+var SetCustomConflictMarkerSize = func(shell *Shell) {
+	shell.CreateFileAndAdd(".gitattributes",
+		fmt.Sprintf("file conflict-marker-size=%d\n", CustomConflictMarkerSize)).
+		Commit("set a custom conflict marker size")
+}
+
 // prepares us for a rebase/merge that has conflicts
 var MergeConflictsSetup = func(shell *Shell) {
 	shell.

pkg/integration/tests/test_list.go

@@ -165,6 +165,8 @@ var tests = []*components.IntegrationTest{
 	config.NegativeRefspec,
 	config.RemoteNamedStar,
 	config.SidePanelsInPerRepoConfig,
+	conflicts.ConflictMarkerSizeNotAutoStaged,
+	conflicts.ConflictMarkerSizeResolve,
 	conflicts.ContinuePromptDismissedWhenResolvedExternally,
 	conflicts.Filter,
 	conflicts.MergeFileBoth,