diff --git a/docs/CONTRIBUTING.en.md b/docs/CONTRIBUTING.en.md
index ea590a7139..21f2b591f3 100644
--- a/docs/CONTRIBUTING.en.md
+++ b/docs/CONTRIBUTING.en.md
@@ -19,22 +19,22 @@ When you want to add a feature or fix a bug, first have the design and policy re
 Also, when you start implementation, assign yourself to the Issue (if you cannot do it yourself, ask another member to assign you). By expressing your intention to work the Issue, you can prevent conflicts in the work.
 
 ## Well-known branches
-- **master** branch is tracking the latest release and used for production purposes.
-- **develop** branch is where we work for the next release.
+- **`master`** branch is tracking the latest release and used for production purposes.
+- **`develop`** branch is where we work for the next release.
 	- When you create a PR, basically target it to this branch.
-- **l10n_develop** branch is reserved for localization management.
+- **`l10n_develop`** branch is reserved for localization management.
 
 ## Creating a PR
 Thank you for your PR! Before creating a PR, please check the following:
 - If possible, prefix the title with a keyword that identifies the type of this PR, as shown below.
-  - fix / refactor / feat / enhance / perf / chore
+  - `fix` / `refactor` / `feat` / `enhance` / `perf` / `chore` etc
   - Also, make sure that the granularity of this PR is appropriate. Please do not include more than one type of change or interest in a single PR.
 - If there is an Issue which will be resolved by this PR, please include a reference to the Issue in the text.
 - Please add the summary of the changes to [`CHANGELOG.md`](/CHANGELOG.md). However, this is not necessary for changes that do not affect the users, such as refactoring.
 - Check if there are any documents that need to be created or updated due to this change.
 - If you have added a feature or fixed a bug, please add a test case if possible.
 - Please make sure that tests and Lint are passed in advance.
-  - You can run it with `npm run test` and `npm run lint`.
+  - You can run it with `npm run test` and `npm run lint`. [See more info](#testing)
 - If this PR includes UI changes, please attach a screenshot in the text.
 
 Thanks for your cooperation 🤗
@@ -48,3 +48,19 @@ The owner [@syuilo](https://github.com/syuilo) merges the PR into the develop br
 If your language is not listed in Crowdin, please open an issue.
 
 ![Crowdin](https://d322cqt584bo4o.cloudfront.net/misskey/localized.svg)
+
+## Testing
+- Test codes are located in [`/test`](/test).
+
+### Run test
+```
+npm run test
+```
+
+#### Run specify test
+```
+npx cross-env TS_NODE_FILES=true TS_NODE_TRANSPILE_ONLY=true TS_NODE_PROJECT="./test/tsconfig.json" npx mocha test/foo.ts --require ts-node/register
+```
+
+### e2e tests
+TODO