git merge command - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a fast-forward merge

You have a branch feature that is ahead of main with new commits. You run git checkout main and then git merge feature. What is the output?

Git

git checkout main
git merge feature

A

Updating abc1234..def5678
Fast-forward

B

Auto-merging file.txt
CONFLICT (content): Merge conflict in file.txt

C Already up to date.

D error: You have unmerged files.

💡 Hint

Think about what happens when the target branch has no new commits since the source branch diverged.

When the target branch has no new commits and the source branch is ahead, git performs a fast-forward merge, updating the target branch pointer to the source branch commit. The output shows the commit range and 'Fast-forward'.

💻 Command Output

intermediate

Result of merging with conflicts

You try to merge branch feature into main, but both branches changed the same lines in a file. What output does git merge feature produce?

Git

git checkout main
git merge feature

A

Auto-merging file.txt
CONFLICT (content): Merge conflict in file.txt
Automatic merge failed; fix conflicts and then commit the result.

B Already up to date.

C error: Your local changes to the following files would be overwritten by merge

D Fast-forward

💡 Hint

Conflicts happen when the same lines are changed differently in both branches.

Git reports the conflicting file and shows a conflict message. It stops the merge and asks you to fix conflicts manually before committing.

❓ Configuration

advanced

Configuring merge strategy for a branch

You want to always use the 'ours' merge strategy when merging the experimental branch into main. Which git config command sets this behavior?

A git config branch.main.merge '--strategy=ours'

B git config branch.experimental.mergeoptions '--strategy=ours'

C git config branch.experimental.merge '--strategy=ours'

D git config branch.main.mergeoptions '--strategy=ours'

💡 Hint

The config key for merge options is under the branch name you want to configure.

The mergeoptions config is set per branch and applies when merging into that branch. To always use 'ours' strategy when merging experimental into main, set it under branch.main.mergeoptions.

❓ Troubleshoot

advanced

Cause of 'fatal: refusing to merge unrelated histories' error

You run git merge feature but get the error fatal: refusing to merge unrelated histories. What is the most likely cause?

A There are uncommitted changes in the working directory.

B The branches come from repositories with no common commit history.

C The feature branch has merge conflicts.

D The main branch is already up to date.

💡 Hint

Think about what it means for histories to be unrelated.

This error happens when git tries to merge two branches that do not share any common ancestor commit, often because they come from different repositories initialized separately.

🔀 Workflow

expert

Correct sequence to merge a remote branch with conflict resolution

You want to merge the remote branch origin/feature into your local main branch and resolve conflicts if any. What is the correct order of commands?

A 1,3,2,4

B 1,2,3,4

C 2,1,3,4

D 2,3,1,4

💡 Hint

You must update your remote tracking branches before merging.

First fetch updates remote branches, then checkout main, merge the remote feature branch, and finally resolve conflicts if any before committing.