How to check compare changes on a topic branch to master

If I want to compare changes on a topic branch to master, I find it easiest and safest to do the following:

Copygit checkout master
git checkout -b trial_merge
git merge topic_branch

After completing the merge, it is easy to see the consolidated change from master

Copygit diff master

When done, simply delete the trial_merge branch

Copygit checkout master
git branch -D trial_merge

This way, the master branch never changes.

In TortoiseGit

1. Switch/Checkout master
2. Create Branch... based on master, name it trialmerge
3. Switch/Checkout trialmerge
4. Git Merge... topicbranch
5. Diff with previos version
6. check the diff
7. Switch/Checkout master
8. delete trialmerge