feat: update badge alias from coverage/coverage-summary.json (#5)

Badge format
```
![code coverage](https://img.shields.io/badge/code--coverage-80-brightgreen)
```

Author: bahmutov

.github/workflows/ci.yml

@@ -19,6 +19,9 @@ jobs:
       - name: Check totals 🛡
         run: node bin/check-total --min 90
 
+      - name: Update code coverage badge 🥇
+        run: node bin/update-badge
+
       - name: Semantic Release 🚀
         uses: cycjimmy/semantic-release-action@v2
         env:

README.md

@@ -1,4 +1,4 @@
-# check-code-coverage [![ci status][ci image]][ci url]
+# check-code-coverage [![ci status][ci image]][ci url] ![mock coverage](https://img.shields.io/badge/code--coverage-100-brightgreen)
 > Utilities for checking the coverage produced by NYC against extra or missing files
 
 ## Use
@@ -30,5 +30,19 @@ check-total
 check-total --from coverage/coverage-summary.json --min 80
 ```
 
+## update-badge
+
+If your README.md includes Shields.io badge, like this
+
+    ![code coverage](https://img.shields.io/badge/code--coverage-80-brightgreen)
+
+You can update it using statements covered percentage from `coverage/coverage-summary.json` by running
+
+```shell
+update-badge
+```
+
+Related project: [dependency-version-badge](https://github.com/bahmutov/dependency-version-badge)
+
 [ci image]: https://github.com/bahmutov/check-code-coverage/workflows/ci/badge.svg?branch=master
 [ci url]: https://github.com/bahmutov/check-code-coverage/actions

bin/check-total.js

@@ -0,0 +1,36 @@
+#!/usr/bin/env node
+// @ts-check
+
+const path = require('path')
+const fs = require('fs')
+
+function updateBadge() {
+  const coverageFilename = path.join(process.cwd(), 'coverage', 'coverage-summary.json')
+  const coverage = require(coverageFilename)
+  const pct = coverage.total.statements.pct
+
+  const readmeFilename = path.join(process.cwd(), 'README.md')
+  const readmeText = fs.readFileSync(readmeFilename, 'utf8')
+
+  function replaceShield() {
+    // note, Shields.io escaped '-' with '--'
+    const coverageRe = new RegExp(
+      'https://img\\.shields\\.io/badge/code--coverage-(\\d+)-brightgreen',
+    )
+    const coverageBadge = `https://img.shields.io/badge/code--coverage-${pct}-brightgreen`
+
+    const updatedReadmeText = readmeText.replace(
+      coverageRe,
+      coverageBadge,
+    )
+    return updatedReadmeText
+  }
+
+  const maybeChangedText = replaceShield()
+  if (maybeChangedText !== readmeText) {
+    console.log('saving updated readme with coverage %d%%', pct)
+    fs.writeFileSync(readmeFilename, maybeChangedText, 'utf8')
+  }
+}
+
+updateBadge()

bin/update-badge.js

@@ -6,7 +6,8 @@
   "bin": {
     "check-coverage": "bin/check-coverage.js",
     "only-covered": "bin/only-covered.js",
-    "check-total": "bin/check-total.js"
+    "check-total": "bin/check-total.js",
+    "update-badge": "bin/update-badge.js"
   },
   "files": [
     "bin"