start breaking up git struct

pkg/commands/rebasing_test.go

@@ -5,6 +5,8 @@ import (
 	"testing"
 
 	"github.com/go-errors/errors"
+	"github.com/jesseduffield/lazygit/pkg/commands/git_config"
+	"github.com/jesseduffield/lazygit/pkg/commands/models"
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
 	"github.com/jesseduffield/lazygit/pkg/utils"
 	"github.com/stretchr/testify/assert"
@@ -42,7 +44,7 @@ func TestGitCommandRebaseBranch(t *testing.T) {
 	for _, s := range scenarios {
 		t.Run(s.testName, func(t *testing.T) {
 			gitCmd := NewDummyGitCommandWithRunner(s.runner)
-			s.test(gitCmd.RebaseBranch(s.arg))
+			s.test(gitCmd.Rebase.RebaseBranch(s.arg))
 		})
 	}
 }
@@ -70,7 +72,74 @@ func TestGitCommandSkipEditorCommand(t *testing.T) {
 		return "", nil
 	})
 	gitCmd := NewDummyGitCommandWithRunner(runner)
-	err := gitCmd.runSkipEditorCommand(commandStr)
+	err := gitCmd.Rebase.runSkipEditorCommand(commandStr)
 	assert.NoError(t, err)
 	runner.CheckForMissingCalls()
 }
+
+func TestGitCommandDiscardOldFileChanges(t *testing.T) {
+	type scenario struct {
+		testName               string
+		gitConfigMockResponses map[string]string
+		commits                []*models.Commit
+		commitIndex            int
+		fileName               string
+		runner                 *oscommands.FakeCmdObjRunner
+		test                   func(error)
+	}
+
+	scenarios := []scenario{
+		{
+			testName:               "returns error when index outside of range of commits",
+			gitConfigMockResponses: nil,
+			commits:                []*models.Commit{},
+			commitIndex:            0,
+			fileName:               "test999.txt",
+			runner:                 oscommands.NewFakeRunner(t),
+			test: func(err error) {
+				assert.Error(t, err)
+			},
+		},
+		{
+			testName:               "returns error when using gpg",
+			gitConfigMockResponses: map[string]string{"commit.gpgsign": "true"},
+			commits:                []*models.Commit{{Name: "commit", Sha: "123456"}},
+			commitIndex:            0,
+			fileName:               "test999.txt",
+			runner:                 oscommands.NewFakeRunner(t),
+			test: func(err error) {
+				assert.Error(t, err)
+			},
+		},
+		{
+			testName:               "checks out file if it already existed",
+			gitConfigMockResponses: nil,
+			commits: []*models.Commit{
+				{Name: "commit", Sha: "123456"},
+				{Name: "commit2", Sha: "abcdef"},
+			},
+			commitIndex: 0,
+			fileName:    "test999.txt",
+			runner: oscommands.NewFakeRunner(t).
+				Expect(`git rebase --interactive --autostash --keep-empty abcdef`, "", nil).
+				Expect(`git cat-file -e HEAD^:"test999.txt"`, "", nil).
+				Expect(`git checkout HEAD^ -- "test999.txt"`, "", nil).
+				Expect(`git commit --amend --no-edit --allow-empty`, "", nil).
+				Expect(`git rebase --continue`, "", nil),
+			test: func(err error) {
+				assert.NoError(t, err)
+			},
+		},
+		// test for when the file was created within the commit requires a refactor to support proper mocks
+		// currently we'd need to mock out the os.Remove function and that's gonna introduce tech debt
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			gitCmd := NewDummyGitCommandWithRunner(s.runner)
+			gitCmd.gitConfig = git_config.NewFakeGitConfig(s.gitConfigMockResponses)
+			s.test(gitCmd.Rebase.DiscardOldFileChanges(s.commits, s.commitIndex, s.fileName))
+			s.runner.CheckForMissingCalls()
+		})
+	}
+}