git diff between branches - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of git diff between two branches

What will be the output of the following command if branch feature has 3 new lines added to app.py compared to main?

Git

git diff main..feature -- app.py

A Shows the commit history of <code>feature</code> branch

B Shows all files changed between <code>main</code> and <code>feature</code> including <code>app.py</code>

C Shows no output because <code>git diff</code> does not compare branches

D Shows the 3 new lines added in <code>app.py</code> compared to <code>main</code>

💡 Hint

Use git diff branch1..branch2 to see differences between branches.

The command git diff main..feature -- app.py shows the changes in app.py that exist in feature but not in main. It only shows the diff for that file.

🧠 Conceptual

intermediate

Understanding git diff branch range syntax

Which of the following correctly describes what git diff branchA..branchB shows?

A All commits that exist in both branches

B Changes needed to convert <code>branchB</code> into <code>branchA</code>

C Changes needed to convert <code>branchA</code> into <code>branchB</code>

D The list of files changed in <code>branchA</code> only

💡 Hint

Think about which branch is the base and which is the target.

git diff branchA..branchB shows the changes that would transform branchA into branchB. It compares the tips of the two branches.

❓ Troubleshoot

advanced

Why does git diff show no output between branches?

You run git diff main..feature but see no output, even though you expect differences. What could be a reason?

A Both branches point to the same commit, so no differences exist

B You forgot to add files to the staging area

C The command only shows differences in the working directory, not between branches

D You need to run <code>git fetch</code> before <code>git diff</code>

💡 Hint

Check if the branches have diverged commits.

If both branches point to the same commit, there are no differences to show, so git diff outputs nothing.

🔀 Workflow

advanced

Using git diff to review changes before merging

You want to review all changes in branch feature compared to main before merging. Which command is best?

A git diff main..feature

B git diff feature..main

C git merge feature

D git log main..feature

💡 Hint

Think about which branch is the base and which is the feature.

git diff main..feature shows all changes in feature that are not in main. This helps review before merging.

✅ Best Practice

expert

Best practice for comparing branches with uncommitted changes

You have uncommitted changes in your working directory. You want to compare feature branch with main. What is the best practice?

A Stash or commit your changes before running <code>git diff main..feature</code>

B Run <code>git diff main..feature</code> directly; uncommitted changes do not affect it

C Use <code>git diff --cached main..feature</code> to ignore uncommitted changes

D Reset your working directory to discard uncommitted changes before diff

💡 Hint

git diff between branches compares branch tips and ignores working directory.

git diff main..feature compares the trees at the tips of the branches, unaffected by uncommitted changes in the working directory or index.