Reordering commits in Git - Practice Problems & Coding Challenges

Challenge - 5 Problems

🔀 Workflow

intermediate

Reordering commits using interactive rebase

You want to reorder the last 4 commits in your branch so that the oldest commit becomes the newest. Which command sequence correctly starts this process?

A git rebase -i HEAD~5

B git rebase -i HEAD~1

C git rebase -i HEAD~3

D git rebase -i HEAD~4

💡 Hint

Remember that HEAD~N means the commit N steps before HEAD, and you want to include exactly 4 commits.

To reorder the last 4 commits, you need to start an interactive rebase from HEAD~4. This includes the last 4 commits for editing.

💻 Command Output

intermediate

Result of reordering commits in interactive rebase

After running 'git rebase -i HEAD~3' and swapping the order of the last two commits in the editor, what will be the effect on the commit history?

A The rebase will fail with a conflict error

B The last two commits will swap places in the history

C The commit messages will be swapped but the order stays the same

D The commits will be merged into one commit

💡 Hint

Interactive rebase allows you to reorder commits by changing their order in the editor.

Swapping the order of commits in the interactive rebase editor changes their order in the commit history after the rebase completes.

❓ Troubleshoot

advanced

Resolving conflicts during commit reordering

During an interactive rebase to reorder commits, you encounter a conflict. What is the correct sequence of commands to resolve the conflict and continue the rebase?

A Fix the conflict, git add <files>, git rebase --continue

B Fix the conflict, git commit, git rebase --skip

C Fix the conflict, git reset, git rebase --abort

D Fix the conflict, git stash, git rebase --continue

💡 Hint

After fixing conflicts, you need to stage the changes before continuing the rebase.

When a conflict occurs during rebase, fix the files, stage them with git add, then run git rebase --continue to proceed.

🧠 Conceptual

advanced

Understanding the effect of reordering commits on commit hashes

What happens to the commit hashes of the reordered commits after completing an interactive rebase that changes their order?

A All reordered commits get new hashes because their parent commits changed

B Commit hashes remain the same since content is unchanged

C Only the first commit in the reordered list gets a new hash

D Hashes change only if commit messages are edited

💡 Hint

Commit hashes depend on the commit content and its parent commit hash.

Changing the order changes parent commits, so all reordered commits get new hashes.

✅ Best Practice

expert

Best practice when reordering commits on a shared branch

You want to reorder commits on a branch that others have already pulled. What is the best practice to avoid problems?

A Force push immediately after reordering to update remote

B Delete the remote branch and push a new one with reordered commits

C Avoid reordering commits on shared branches to prevent rewriting history

D Rebase and merge the branch into main without pushing

💡 Hint

Rewriting history on shared branches can cause confusion and conflicts for others.

Reordering commits rewrites history. On shared branches, this can cause problems for collaborators, so it is best avoided.

Practice

1. What is the main purpose of using git rebase -i when working with commits?

easy

A. To create a new branch from the current commit

B. To reorder, edit, or squash commits interactively

C. To merge two branches automatically

D. To delete the entire commit history

Solution

1. Step 1: Understand the function of git rebase -i

   This command opens an interactive editor allowing you to reorder, edit, or squash commits.

2. Step 2: Compare with other options

   Creating branches, merging, or deleting history are not the main purposes of this command.

3. Final Answer:

   To reorder, edit, or squash commits interactively -> Option B

4. Quick Check:

   Interactive rebase = reorder commits [OK]

Hint: Use interactive rebase to reorder commits easily [OK]

Common Mistakes:

• Confusing rebase with branch creation
• Thinking rebase deletes history
• Mixing rebase with merge commands

2. Which of the following is the correct command to start an interactive rebase for the last 3 commits?

easy

A. git rebase -i HEAD~3

B. git rebase -i HEAD^3

C. git rebase -i HEAD~

D. git rebase -i HEAD^^3

Solution

1. Step 1: Recall the syntax for interactive rebase

   The correct syntax uses HEAD~N to specify the last N commits, so HEAD~3 means last 3 commits.

2. Step 2: Check other options for syntax errors

   HEAD^3 and HEAD^^3 are invalid for this purpose; HEAD~ is incomplete.

3. Final Answer:

   git rebase -i HEAD~3 -> Option A

4. Quick Check:

   Use HEAD~N for last N commits [OK]

Hint: Use HEAD~N to specify last N commits in rebase [OK]

Common Mistakes:

• Using caret (^) incorrectly for commit range
• Omitting the number after ~
• Confusing HEAD~ with HEAD^

3. Given the following interactive rebase todo list:

pick a1b2c3 Commit A
pick d4e5f6 Commit B
pick 789abc Commit C

If you change it to:

pick d4e5f6 Commit B
pick a1b2c3 Commit A
pick 789abc Commit C

What will be the order of commits after the rebase?

medium

A. Commit B, Commit A, Commit C

B. Commit A, Commit B, Commit C

C. Commit C, Commit B, Commit A

D. Commit A, Commit C, Commit B

Solution

1. Step 1: Understand the todo list order

   The interactive rebase applies commits in the order listed. Changing the order changes commit history order.

2. Step 2: Apply the new order

   New order is Commit B, then Commit A, then Commit C.

3. Final Answer:

   Commit B, Commit A, Commit C -> Option A

4. Quick Check:

   Rebase applies commits in listed order [OK]

Hint: Order commits in todo list to reorder history [OK]

Common Mistakes:

• Assuming original order stays after rebase
• Confusing commit hashes with order
• Ignoring the todo list sequence

4. You ran git rebase -i HEAD~3 and changed the order of commits, but Git shows a conflict error. What is the best way to fix this?

medium

A. Force push the branch without resolving conflicts

B. Abort the rebase with git rebase --abort and try again

C. Delete the .git folder and start over

D. Manually resolve conflicts, then run git rebase --continue

Solution

1. Step 1: Understand rebase conflict handling

   When conflicts occur during rebase, you must manually fix them in files.

2. Step 2: Continue rebase after resolving conflicts

   After fixing conflicts, run git rebase --continue to proceed.

3. Final Answer:

   Manually resolve conflicts, then run git rebase --continue -> Option D

4. Quick Check:

   Fix conflicts + git rebase --continue [OK]

Hint: Fix conflicts, then continue rebase with git rebase --continue [OK]

Common Mistakes:

• Ignoring conflicts and force pushing
• Aborting rebase without trying to fix
• Deleting .git folder which loses repo data

5. You want to reorder the last 4 commits to put the oldest commit last without changing their content. Which sequence of commands correctly achieves this?

hard

A. Run git reset --hard HEAD~4 then cherry-pick commits in new order

B. Run git merge --reorder HEAD~4 to reorder commits automatically

C. Run git rebase -i HEAD~4, then move the first commit line to the bottom in the editor

D. Run git rebase -i HEAD~3 and swap the last two commits

Solution

1. Step 1: Use interactive rebase on last 4 commits

   Running git rebase -i HEAD~4 opens the last 4 commits for editing order.

2. Step 2: Move the oldest commit line to the bottom

   In the editor, reorder lines so the oldest commit is last, preserving content.

3. Final Answer:

   Run git rebase -i HEAD~4, then move the first commit line to the bottom in the editor -> Option C

4. Quick Check:

   Interactive rebase + reorder lines = reorder commits [OK]

Hint: Use interactive rebase and reorder lines to change commit order [OK]

Common Mistakes:

• Using reset which loses commit history
• Trying non-existent git merge --reorder command
• Using wrong commit range in rebase