feat: add --from file support to check-coverage

Author: bahmutov

.nyc_output/no-information.json

@@ -0,0 +1,6 @@
+{
+  "no-coverage.js": {
+    "path": "no-coverage.js",
+    "s": {}
+  }
+}

README.md

@@ -17,6 +17,7 @@ By default `only-covered` script reads `.nyc_output/out.json` file from the curr
 
 ```shell
 only-covered --from examples/exclude-files/coverage/coverage-final.json main.js
+check-coverage --from examples/exclude-files/coverage/coverage-final.json main.js
 ```
 
 [ci image]: https://github.com/bahmutov/check-code-coverage/workflows/ci/badge.svg?branch=master

bin/check-coverage.js

@@ -1,13 +1,21 @@
 #!/usr/bin/env node
 // @ts-check
-const { join } = require('path')
+const { join, resolve } = require('path')
+const arg = require('arg')
 
-const filename = process.argv[2]
+const args = arg({
+  '--from': String, // input filename, by default ".nyc_output/out.json"
+})
+
+const filename = args._[0]
 if (!filename) {
   console.error('Usage: node %s <file name>', __filename)
   process.exit(1)
 }
-const coverageFilename = join(process.cwd(), '.nyc_output', 'out.json')
+
+const fromFilename = args['--from'] || join('.nyc_output', 'out.json')
+const coverageFilename = resolve(fromFilename)
+
 const coverage = require(coverageFilename)
 const fileCoverageKey = Object.keys(coverage).find(name => {
   const fileCover = coverage[name]