Rebase vs. merge

To illustrate rebasing we consider the following situation - we wish to merge master into devel:

Now you know how to do it:

$ git checkout devel
$ git merge master

This creates a merge commit:

But there is an alternative for integrating master commits into the devel branch:

$ git checkout devel
$ git rebase master

• git rebase replays the branch commits b1 to b3 on top of master.
• As if they were committed after c5.
• This changes history (notice that the commits b1 to b3 have been replaced by b1* to b3*).
• Discuss the advantages and disadvantages.

Advantages and disadvantages

• git rebase makes “merges” producing a linear history.
• git merge resolves all conflicts in a single commit, with git rebase each commit may need conflict resolution.
• git rebase may invalidate tests.
• git merge preserves chronology of commits and creates explicit merge commits (unless fast-forward).
• git rebase can change chronology of commits.
• When working with others do not rebase commits that other people depend on (history has changed).
• Reference: “Treehouse of Horror V: Time and Punishment”, The Simpsons (1994).

Question

• How does rebasing affect testing?