Git Bisect is a powerful tool that helps you identify the commit that introduced a bug or issue in your codebase. It uses a binary search algorithm to efficiently narrow down the problematic commit by checking out different commits and asking you whether the issue is present or not.

• Binary Search: Git Bisect uses a binary search algorithm to find the commit that introduced the bug. This means it will split the range of commits in half and test the midpoint, reducing the number of commits to check by half each time.
• Good and Bad Commits: You need to specify a known good commit (where the bug is not present) and a known bad commit (where the bug is present). Git Bisect will then help you find the exact commit that introduced the bug.

1. Start Bisecting: Initialize the bisect process by specifying the good and bad commits.
2. Mark Commits: For each commit checked out by Git Bisect, you need to mark it as good or bad.
3. Identify the Culprit: Git Bisect will eventually narrow down to the commit that introduced the bug.

Let's walk through a practical example to understand how Git Bisect works.

First, navigate to your repository and start the bisect process by specifying the good and bad commits.

Replace <known-good-commit> with the hash of a commit where the bug was not present.

Git will check out a commit in the middle of the range. You need to test your code and mark the commit as good or bad.

Repeat this process until Git Bisect identifies the problematic commit.

Once Git Bisect has narrowed down the range, it will output the commit that introduced the bug.

After identifying the problematic commit, end the bisect session.

Let's assume you have a repository with the following commit history:

You know that the bug was introduced in commit e5f6g7h and was not present in commit c3d4e5f.

1. Start bisecting:

   git bisect start
   git bisect bad e5f6g7h
   git bisect good c3d4e5f
   

2. Git checks out commit d4e5f6g. Test your code:

   # Test your code
   # If the bug is present
   git bisect bad
   

3. Git checks out commit b2c3d4e. Test your code:

   # Test your code
   # If the bug is not present
   git bisect good
   

4. Git checks out commit d4e5f6g again. Test your code:

   # Test your code
   # If the bug is present
   git bisect bad
   

5. Git identifies d4e5f6g as the first bad commit.

   # Output
   # d4e5f6g is the first bad commit
   

6. End bisecting:

   git bisect reset
   

1. Clone a sample repository with a known bug.
2. Use Git Bisect to identify the commit that introduced the bug.
3. Document the steps you took and the commit hash that introduced the bug.

1. Clone the repository:

   git clone https://github.com/example/sample-repo.git
   cd sample-repo
   

2. Start bisecting:

   git bisect start
   git bisect bad HEAD
   git bisect good <known-good-commit>
   

3. Mark commits as good or bad based on your tests:

   # Test your code
   git bisect bad  # or git bisect good
   

4. Identify the problematic commit and end bisecting:

   git bisect reset
   

Git Bisect is an invaluable tool for debugging and identifying the commit that introduced a bug. By leveraging a binary search algorithm, it efficiently narrows down the range of commits, saving you time and effort. Practice using Git Bisect in your projects to become proficient in quickly identifying and resolving issues.