To use Git bisect to find the commit that introduced a bug, follow these steps:
Identify a known good commit: Start by identifying a commit in your Git history where the bug was not present. This will serve as the "good" reference point.
Identify the known bad commit: Identify a commit that introduced the bug or when you first noticed the bug. This will serve as the "bad" reference point.
Start the bisect process: Open your terminal or command prompt and navigate to the repository where the bug is present. Run the command git bisect start. This command starts the bisect process and puts Git into a "bisecting state."
Mark the bad commit: Run the command git bisect bad <commit> to mark the known bad commit that introduced the bug. Replace <commit> with the commit hash, branch name, or any other identifier that points to the commit.
Mark the good commit: Run the command git bisect good <commit> to mark the known good commit where the bug was not present. Replace <commit> with the commit hash, branch name, or any other identifier that points to the commit.
Git will automatically checkout a commit between the good and the bad commits. Git will prompt you to test this commit and determine if the bug is present or not.
Test the commit: After checking out each commit, test for the presence of the bug. If the bug is present, run the command git bisect bad to mark the commit as bad. If the bug is not present, run the command git bisect good to mark the commit as good.
Repeat until the bug is isolated: Git will continue providing commits to test until it isolates the exact commit that introduced the bug. This process follows a binary search algorithm, quickly narrowing down the search range.
Identify the bad commit: Once Git has found the commit that introduced the bug, it will print the commit information to the terminal. You can then examine this commit to understand what caused the bug.
End the bisect process: Run the command git bisect reset to end the bisect process and return your repository to its original state.
By using Git bisect, you can effectively pinpoint the commit that introduced a bug, making it easier to debug and fix the issue.