migrate discard staged changes test

pkg/integration/components/file_system.go

@@ -24,3 +24,26 @@ func (self *FileSystem) PathNotPresent(path string) {
 		return os.IsNotExist(err), fmt.Sprintf("Expected path '%s' to not exist, but it does", path)
 	})
 }
+
+// Asserts that the file at the given path has the given content
+func (self *FileSystem) FileContainsContent(path string, matcher *matcher) {
+	self.assertWithRetries(func() (bool, string) {
+		_, err := os.Stat(path)
+		if os.IsNotExist(err) {
+			return false, fmt.Sprintf("Expected path '%s' to not exist, but it does", path)
+		}
+
+		output, err := os.ReadFile(path)
+		if err != nil {
+			return false, fmt.Sprintf("Expected error when reading file content at path '%s': %s", path, err.Error())
+		}
+
+		strOutput := string(output)
+
+		if ok, errMsg := matcher.context("").test(strOutput); !ok {
+			return false, fmt.Sprintf("Unexpected content in file %s: %s", path, errMsg)
+		}
+
+		return true, ""
+	})
+}

pkg/integration/tests/file/discard_staged_changes.go

@@ -0,0 +1,52 @@
+package file
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var DiscardStagedChanges = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Discarding staged changes",
+	ExtraCmdArgs: "",
+	Skip:         false,
+	SetupConfig: func(config *config.AppConfig) {
+	},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateFileAndAdd("fileToRemove", "original content")
+		shell.CreateFileAndAdd("file2", "original content")
+		shell.Commit("first commit")
+
+		shell.CreateFile("file3", "original content")
+		shell.UpdateFile("fileToRemove", "new content")
+		shell.UpdateFile("file2", "new content")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Files().
+			IsFocused().
+			Lines(
+				Contains(` M file2`).IsSelected(),
+				Contains(` M fileToRemove`),
+				Contains(`?? file3`),
+			).
+			SelectNextItem().
+			PressPrimaryAction().
+			Lines(
+				Contains(` M file2`),
+				Contains(`M  fileToRemove`).IsSelected(),
+				Contains(`?? file3`),
+			).
+			Press(keys.Files.ViewResetOptions)
+
+		t.ExpectPopup().Menu().Title(Equals("")).Select(Contains("discard staged changes")).Confirm()
+
+		// staged file has been removed
+		t.Views().Files().
+			Lines(
+				Contains(` M file2`),
+				Contains(`?? file3`).IsSelected(),
+			)
+
+		// the file should have the same content that it originally had, given that that was committed already
+		t.FileSystem().FileContainsContent("fileToRemove", Equals("original content"))
+	},
+})

pkg/integration/tests/tests.go

@@ -53,6 +53,7 @@ var tests = []*components.IntegrationTest{
 	custom_commands.MultiplePrompts,
 	file.DirWithUntrackedFile,
 	file.DiscardChanges,
+	file.DiscardStagedChanges,
 	interactive_rebase.AmendMerge,
 	interactive_rebase.One,
 	stash.Rename,