Three-way merge in Git - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to start a three-way merge in Git.

Git

git merge [1]

Drag options to blanks, or click blank then click option'

Abranch

Bcommit

Crebase

Dcheckout

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'commit' instead of 'branch' causes an error.

Using 'rebase' changes history instead of merging.

The git merge branch command merges the specified branch into the current branch using a three-way merge if needed.

2fill in blank

medium

Complete the command to abort a conflicted merge.

Git

git merge --[1]

Drag options to blanks, or click blank then click option'

Askip

Babort

Ccontinue

Dreset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'continue' tries to finish the merge instead of aborting.

Using 'reset' is a different command and does not abort merge.

The git merge --abort command stops the merge and returns the repository to the state before the merge started.

3fill in blank

hard

Fix the error in the command to view the merge base commit.

Git

git merge-base [1] feature

Drag options to blanks, or click blank then click option'

Acommit

Bbranch

CHEAD

Dorigin

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'branch' or 'commit' causes errors because they are not valid references here.

Using 'origin' refers to a remote, not a commit or branch.

The git merge-base HEAD feature command finds the common ancestor commit between the current branch (HEAD) and the feature branch.

4fill in blank

hard

Fill both blanks to create a dictionary of files changed and their status after a merge.

Git

git diff --name-status [1] [2]

Drag options to blanks, or click blank then click option'

AHEAD

BMERGE_HEAD

Corigin/main

Dfeature

Attempts:

3 left

💡 Hint

Common Mistakes

Using HEAD instead of MERGE_HEAD shows differences with current branch, not merge target.

Using origin/main mixes remote with local merge references.

The command git diff --name-status MERGE_HEAD feature shows the list of files and their change status between the merge commit and the feature branch.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that filters files changed in a merge with status 'M' (modified).

Git

changed_files = { [1]: [2] for [3] in files if status == 'M' }

Drag options to blanks, or click blank then click option'

Afilename

Bstatus

Dfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same variable name for key and loop variable causes confusion.

Not filtering by status 'M' includes unwanted files.

This dictionary comprehension creates a dictionary where keys are filenames and values are their status, but only for files with status 'M' (modified).

Practice

1. What is the main purpose of a three-way merge in Git?

easy

A. To combine changes from two branches using a common base

B. To delete a branch after merging

C. To create a new branch from the current branch

D. To reset the current branch to a previous commit

Solution

1. Step 1: Understand the concept of three-way merge

   A three-way merge uses the common ancestor of two branches to combine their changes safely.

2. Step 2: Identify the purpose in Git workflow

   This process helps merge changes from two branches without losing work, especially when both branches have edits.

3. Final Answer:

   To combine changes from two branches using a common base -> Option A

4. Quick Check:

   Three-way merge = combine changes safely [OK]

Hint: Three-way merge combines two branches with a common ancestor [OK]

Common Mistakes:

• Confusing merge with branch deletion
• Thinking merge creates new branches
• Mixing merge with reset commands

2. Which Git command automatically performs a three-way merge when integrating changes from a remote branch?

easy

A. git pull

B. git merge

C. git commit

D. git branch

Solution

1. Step 1: Recall commands that fetch and merge

   git pull fetches changes from a remote branch and merges them locally, often using a three-way merge.

2. Step 2: Differentiate from other commands

   git merge merges branches locally but does not fetch remote changes; git branch manages branches; git commit records changes.

3. Final Answer:

   git pull -> Option A

4. Quick Check:

   git pull = fetch + merge (three-way) [OK]

Hint: git pull fetches and merges remotely with three-way merge [OK]

Common Mistakes:

• Choosing git merge without fetching first
• Confusing git commit with merge
• Using git branch for merging

3. Given the following scenario:

Branch A has file.txt with content: "Hello World"
Branch B modifies file.txt to: "Hello Git"
Common base has file.txt: "Hi World"

What will be the content of file.txt after a successful three-way merge of Branch B into Branch A?

medium

A. "Hello"

B. "Hello Git"

C. "Hello World Git"

D. "Hello World"

Solution

1. Step 1: Identify changes from base to each branch

   Base has "Hi World". Branch A changed "Hi" to "Hello". Branch B changed "Hi" to "Hello" and "World" to "Git".

2. Step 2: Understand three-way merge result

   Since the change "Hi" -> "Hello" is common to both branches, and Branch B has an additional change "World" -> "Git", Git's three-way merge automatically combines them, resulting in "Hello Git".

3. Final Answer:

   "Hello Git" -> Option B

4. Quick Check:

   Three-way merge picks combined changes, here "Hello Git" [OK]

Hint: Merged content reflects changes from both branches via base [OK]

Common Mistakes:

• Assuming content concatenates both changes
• Ignoring base version in merge
• Confusing which branch's changes apply

4. You ran git merge feature but got a conflict in app.js. What should you do to resolve this three-way merge conflict?

medium

A. Run git reset --hard immediately to discard all changes

B. Delete app.js and run git merge --abort

C. Edit app.js to fix conflicts, then run git add app.js and git commit

D. Run git branch -d feature to delete the feature branch

Solution

1. Step 1: Understand merge conflict resolution

   When a conflict occurs, you must manually edit the conflicting file to resolve differences.

2. Step 2: Stage and commit resolved file

   After fixing conflicts in app.js, use git add to stage and then git commit to complete the merge.

3. Final Answer:

   Edit app.js, then git add and git commit -> Option C

4. Quick Check:

   Fix conflicts, stage, commit to resolve merge [OK]

Hint: Fix conflicts manually, then add and commit [OK]

Common Mistakes:

• Deleting files instead of resolving conflicts
• Aborting merge without fixing conflicts
• Deleting branches to fix conflicts

5. You have two branches, main and feature. Both modified the same function in utils.py differently. After running git merge feature into main, a three-way merge conflict occurs. Which approach best resolves this conflict while preserving both changes?

hard

A. Delete feature branch and continue with main unchanged

B. Force merge with git merge --strategy=ours to keep main version only

C. Reset main to the common ancestor commit and retry merge

D. Manually edit utils.py to combine both changes logically, then stage and commit

Solution

1. Step 1: Recognize conflict in same function

   Both branches changed the same function differently, causing a conflict during merge.

2. Step 2: Choose best resolution method

   Manually editing the file to combine both changes logically preserves work from both branches, which is the best practice.

3. Step 3: Stage and commit after resolving

   After editing, stage the file with git add and commit to complete the merge.

4. Final Answer:

   Manually edit utils.py to combine changes, then stage and commit -> Option D

5. Quick Check:

   Manual merge preserves both changes best [OK]

Hint: Edit conflicts to combine changes, then add and commit [OK]

Common Mistakes:

• Using --strategy=ours loses feature changes
• Deleting branches to avoid conflicts
• Resetting loses recent work