Measure test coverage (#16)

* define npm run coverage

* Revert "define npm run coverage"

This reverts commit 32133d33412105d167226ac31c4f7875f85716ab.

* use coverallsapp/github-action@master

* Give --coverage option to npm test

* Add coveralls badge

.github/workflows/test.yml

@@ -14,10 +14,13 @@ jobs:
     - run: |
         npm install
         npm run all
+    - uses: coverallsapp/github-action@master
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
   test: # make sure the action works on a clean machine without building
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v1
     - uses: ./
-      with: 
-        milliseconds: 1000
+      with:
+        issue_title: npm audit run by test job

README.md

@@ -1,5 +1,7 @@
 # npm audit action
 
+[![Coverage Status](https://coveralls.io/repos/github/oke-py/npm-audit-action/badge.svg?branch=master)](https://coveralls.io/github/oke-py/npm-audit-action?branch=master)
+
 GitHub Action to run `npm audit`
 
 If vulnerabilities are found by `npm audit`, it creates the following GitHub Issue.

package.json

@@ -11,7 +11,7 @@
     "lint": "eslint src/**/*.ts",
     "pack": "ncc build",
     "test": "jest",
-    "all": "npm run build && npm run format && npm run lint && npm run pack && npm test"
+    "all": "npm run build && npm run format && npm run lint && npm run pack && npm test -- --coverage"
   },
   "repository": {
     "type": "git",