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Technical contributor onboarding/Resolve merge conflict

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Introduction

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We will try to resolve the conflict for patch gerrit:591060. You can see that the patch has a merge conflict in two places, at the top of the page, and at the bottom of the page.

Merge conflict visible at the top of the page. Merge conflict visible at the bottom of the page.

Pull

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Pull the latest commit from the TemplateWizard repository. 

cd mediawiki/extensions/TemplateWizard
git checkout master
git pull origin master

Fetch

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Get the patch from Gerrit. 

git review -d 591060

Rebase

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Rebase the patch on top of the master branch. Git will let you know that there's a merge conflict. 

git rebase master

First, rewinding head to replay your work on top of it...
Applying: Upgraded  WebdriverIO from v4 to v5
Using index info to reconstruct a base tree...
M	package-lock.json
M	package.json
Falling back to patching base and 3-way merge...
Auto-merging package.json
CONFLICT (content): Merge conflict in package.json
Auto-merging package-lock.json
CONFLICT (content): Merge conflict in package-lock.json
error: Failed to merge in the changes.
Patch failed at 0001 Upgraded  WebdriverIO from v4 to v5
hint: Use 'git am --show-current-patch' to see the failed patch
Resolve all conflicts manually, mark them as resolved with
"git add/rm <conflicted_files>", then run "git rebase --continue".
You can instead skip this commit: run "git rebase --skip".
To abort and get back to the state before "git rebase", run "git rebase --abort".

The output from git status is clearer than that from normal Git, so prefer that instead. 

git status

rebase in progress; onto 049a0fd
You are currently rebasing branch 'review/vidhi_mody/test' on '049a0fd'.
  (fix conflicts and then run "git rebase --continue")
  (use "git rebase --skip" to skip this patch)
  (use "git rebase --abort" to check out the original branch)

Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

	modified:   tests/selenium/.eslintrc.json
	modified:   tests/selenium/specs/TemplateWizard.js
	modified:   tests/selenium/wdio.conf.js

Unmerged paths:
  (use "git reset HEAD <file>..." to unstage)
  (use "git add <file>..." to mark resolution)

	both modified:   package-lock.json
	both modified:   package.json

Conflict

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This is the important part of the output. The rest can be ignored for now. 

	both modified:   package-lock.json
	both modified:   package.json

Both your patch and master branches have modified files:

  • package-lock.json * package.json.

Resolve package.json

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We will first resolve the conflict in package.json: 

cat package.json 

{
	"private": true,
	"scripts": {
		"selenium-daily": "npm run selenium-test",
		"selenium-test": "wdio tests/selenium/wdio.conf.js",
		"test": "grunt test"
	},
	"devDependencies": {
<<<<<<< HEAD
		"eslint-config-wikimedia": "0.15.3",
		"grunt": "1.1.0",
		"grunt-banana-checker": "0.9.0",
		"grunt-eslint": "22.0.0",
		"grunt-stylelint": "0.15.0",
		"stylelint-config-wikimedia": "0.10.1",
		"wdio-mediawiki": "0.5.0",
		"wdio-mocha-framework": "0.6.4",
		"wdio-spec-reporter": "0.1.5",
		"webdriverio": "4.14.4"
=======
		"@wdio/cli": "5.22.4",
		"@wdio/junit-reporter": "5.22.4",
		"@wdio/local-runner": "5.22.4",
		"@wdio/mocha-framework": "5.18.7",
		"@wdio/spec-reporter": "5.22.4",
		"@wdio/sync": "5.18.7",
		"eslint-config-wikimedia": "0.15.0",
		"grunt": "1.1.0",
		"grunt-banana-checker": "0.9.0",
		"grunt-eslint": "22.0.0",
		"grunt-stylelint": "0.14.0",
		"stylelint-config-wikimedia": "0.9.0",
		"wdio-mediawiki": "1.0.0",
		"webdriverio": "5.22.4"
>>>>>>> Upgraded  WebdriverIO from v4 to v5
	}
}

This is not very readable and probably looks more scary than it is.

  • The code portion between <<<<<<< HEAD and ======= is in the master branch.
  • The code portion between ======= and >>>>>>> Upgraded WebdriverIO from v4 to v5 is in your patch.

Note that a few packages are updated in master.

  • eslint-config-wikimedia from 0.15.0 to 0.15
  • grunt-stylelint from 0.14.0 to 0.15.0
  • stylelint-config-wikimedia from 0.9.0 to 0.10.1

Edit the file so that it looks like this: 

cat package.json

{
	"private": true,
	"scripts": {
		"selenium-daily": "npm run selenium-test",
		"selenium-test": "wdio tests/selenium/wdio.conf.js",
		"test": "grunt test"
	},
	"devDependencies": {
		"@wdio/cli": "5.22.4",
		"@wdio/junit-reporter": "5.22.4",
		"@wdio/local-runner": "5.22.4",
		"@wdio/mocha-framework": "5.18.7",
		"@wdio/spec-reporter": "5.22.4",
		"@wdio/sync": "5.18.7",
		"eslint-config-wikimedia": "0.15.3",
		"grunt": "1.1.0",
		"grunt-banana-checker": "0.9.0",
		"grunt-eslint": "22.0.0",
		"grunt-stylelint": "0.15.0",
		"stylelint-config-wikimedia": "0.10.1",
		"wdio-mediawiki": "1.0.0",
		"webdriverio": "5.22.4"
	}
}

Finally, use git add to let Git know that you've resolved the conflict. 

git add package.json

Resolve package-lock.json

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git status will now say there's only one file left to resolve. 

git status
...
	both modified:   package-lock.json

We will now resolve the conflict in package-lock.json. It is automatically generated so you should not edit it manually.

Delete the file and recreate it with npm install: 

rm package-lock.json 
npm install

Next, use git add to let Git know that you've resolved the conflict: 

git add package-lock.json

Check using git status

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git status will now say there are no conflicts left: 

git status

rebase in progress; onto 049a0fd
You are currently rebasing branch 'review/vidhi_mody/test' on '049a0fd'.
  (all conflicts fixed: run "git rebase --continue")

Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

	modified:   package-lock.json
	modified:   package.json
	modified:   tests/selenium/.eslintrc.json
	modified:   tests/selenium/specs/TemplateWizard.js
	modified:   tests/selenium/wdio.conf.js

Rebase

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Continue the rebase using git rebase --continue: 

git rebase --continue

Applying: Upgraded  WebdriverIO from v4 to v5

Using git status now shows: 

git status

On branch review/vidhi_mody/test
Your branch is ahead of 'origin/master' by 1 commit.
  (use "git push" to publish your local commits)

nothing to commit, working tree clean

Use your Git diff tool to check the changes in the last patch, and make sure everything looks good.

Push to Gerrit

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Finally, use git review to push the changes to Gerrit. 

git review
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