EXAMPLES: git branches (merge and merging conflicts)

Git branches

   Virtual directories get created for each branch. main/master branch is considered as the branch which has the latest and greatest code. We create branches so each developer can work on its own branch and once the development is finished on a particular stage then it can be reviewed by the code owner and after that, it gets merged into the master branch.

By Default, the master branch gets created when you have your first commit.

Step 1:- List the branches of your local repository. (The branch which has * symbol in front of it is the current branch where we are working).

                git branch

I have only one branch which is master branch and it is my current branch

                *master

Step 2:- List all the commits of your master branch

                 git log --oneline

Step3:- Create a branch for senior developer and name it sdev1.

                git branch sdev1

Step 4:- Create one more branch for junior developer and name it jdev1

                git branch jdev1

Step 5:- List all the branches

                git branch

Step 6:- Switch to sdev1 branch and it should be your current.

                git checkout sdev1

                git branch

Step 7:- List all the files and commits of sdev1 branch. It should have all the commits and files which are present in master branch.

                 ls

                 git log --oneline

Step 8:- Create a new file sdev1.java and commit it in sdev1 branch. It should have a new commit id once commit is done successfully.

                 touch sdev1.java

                 git add sdev1.java

                 git commit -m "sdev1.java file is added in sdev1 branch"

                 git log --oneline  # it should have a new commit

                 ls                       # it show the sdev1.java file

Step 9:- Verify that master branch does not have the commit details which is for sdev1.java file and also sdev1.java file should exist in master branch.

                 git checkout master

                 git log --oneline # it should not show the sdev1.java commit id

                 ls   # sdev1.java file should not be there.

Step 10:- sdev1 wants that his/her code is to be merged into master branch.After merging commit id for sdev1.java addition should be reflected in git log and also sdev1.java file should exist in master branch

                git merge sdev1

                git log --oneline # it should show the sdev1.java commit id 

                ls  # sdev1.java file should be in master branch

Step 11:- Switch to jdev1 branch and commit a new file jdev1.java.

                git checkout jdev1

                touch jdev1.java

                git add jdev1.java

                git commit -m "jdev1.java file is added"

                git log --oneline

Step 12:- Merge jdev1 code into master branch.

               git checkout master

               git merge jdev1

Step 13:- Update sdev1 and jdev1 branch with latest code (master branch)

                git checkout sdev1

                git merge master

                ls

                git checkout jdev1

                git merge master

                ls

Step 14:- jdev is reporting to sdev and all the code changes by jdev is first reviewed by sdev and they merge into master branch and later jdev1 branch get the lastet code from master branch.

          git checkout jdev1

          touch test.java

          git add test.java

          git commit -m "test.java file is added"

                 

# To merge with sdev1 branch

           git checkout sdev1

           git merge jdev1

         

# To merge with master branch

            git checkout master

            git merge sdev1

Now all the branches are in sync.

Merge Conflict

Conflicts generally arise when two people have changed the same lines in a file, or if one developer deleted a file while another developer was modifying it. In these cases, Git cannot automatically determine what is correct. 

Conflicts only affect the developer conducting the merge, the rest of the team is unaware of the conflict. Git will mark the file as being conflicted and halt the merging process. It is then the developers' responsibility to resolve the conflict.

Step 1:- Let's create a new branch jdev2 and he is reporting to sdev1

               git checkout sdev1

               git branch jdev2

Step 2:- sdev1 has asked both junior developers (jdev1 and jdev2) to work on different modules of test.java file and once they finish their work then that code will be reviewed and merge in sdev1 branch and then master branch.

               git checkout jdev1

               echo "This code is added by jdev1" >> test.java

               git add test.java

               git commit -m " test.java file is modified by jdev1"

               git checkout jdev2

               echo "This code is added by jdev2" >> test.java

               git add test.java

               git commit -m " test.java file is modified by jdev2"

Step3:- Merge jdev1 and jdev2 code changes into sdev1 branch if there is any conflict occurs then resolve that conflict.

               git checkout sdev1

               git merge jdev1

               git merge jdev2 # Merge conflict

Step4:- Resolve Merge conflict 

               git mergetool

               update the changes # test.java.orig will be auto-created (make sure to delete)

               cat test.java

               rm test.java.orig

               git commit -m "final test.java file"

Step5:- Update all the branches (jdev1, jdev2 then master) after approval from sdev1

# to merge with jdev1

               git checkout jdev1

               git merge sdev1

               cat test.java

# to merge with jdev2

               git checkout jdev2

               git merge sdev1

               cat test.java

# to merge with master

               git checkout master

               git merge sdev1

               cat test.java

Now all brances are in sync.