feat: configure reporters, default includes json, close #49

Author: bahmutov

Diff for: .gitignore

@@ -6,3 +6,4 @@ coverage/
 dist/
 .cache/
 .vscode/
+cypress-coverage/

Diff for: README.md

@@ -144,6 +144,24 @@ You can specify custom report folder by adding `nyc` object to the `package.json
 }
 ```
 
+## Custom reporters
+
+You can specify custom coverage reporter(s) to use. For example to output text summary and save JSON report in `cypress-coverage` folder set in your `package.json` folder:
+
+```json
+{
+  "nyc": {
+    "report-dir": "cypress-coverage",
+    "reporter": [
+      "text",
+      "json"
+    ]
+  }
+}
+```
+
+**Tip:** find list of reporters [here](https://istanbul.js.org/docs/advanced/alternative-reporters/)
+
 ## Exclude code
 
 You can exclude parts of the code or entire files from the code coverage report. See [Istanbul guide](https://github.com/gotwarlost/istanbul/blob/master/ignoring-code-for-coverage.md). Common cases:

Diff for: package-lock.json

@@ -44,6 +44,7 @@
   "private": false,
   "dependencies": {
     "@cypress/browserify-preprocessor": "2.1.1",
+    "cp-file": "7.0.0",
     "debug": "4.1.1"
   },
   "devDependencies": {

Diff for: package.json

@@ -2,14 +2,26 @@ const istanbul = require('istanbul-lib-coverage')
 const { join } = require('path')
 const { existsSync, mkdirSync, readFileSync, writeFileSync } = require('fs')
 const execa = require('execa')
-const debug = require('debug')('code-coverage')
+const fs = require('fs')
 const { fixSourcePathes } = require('./utils')
 
+const debug = require('debug')('code-coverage')
+
 // these are standard folder and file names used by NYC tools
 const outputFolder = '.nyc_output'
 const coverageFolder = join(process.cwd(), outputFolder)
 const nycFilename = join(coverageFolder, 'out.json')
 
+// there might be custom "nyc" options in the user package.json
+// see https://github.com/istanbuljs/nyc#configuring-nyc
+// potentially there might be "nyc" options in other configuration files
+// it allows, but for now ignore those options
+const pkgFilename = join(process.cwd(), 'package.json')
+const pkg = fs.existsSync(pkgFilename)
+  ? JSON.parse(fs.readFileSync(pkgFilename, 'utf8'))
+  : {}
+const nycOptions = pkg.nyc || {}
+
 function saveCoverage (coverage) {
   if (!existsSync(coverageFolder)) {
     mkdirSync(coverageFolder)
@@ -72,10 +84,21 @@ module.exports = {
       console.warn('Skipping coverage report')
       return null
     }
-    const command = 'nyc'
-    const args = ['report', '--reporter=lcov']
-    debug('saving coverage report using command: %s %s', command, args)
+
+    const reportDir = nycOptions['report-dir'] || './coverage'
+    const reporter = nycOptions['reporter'] || ['lcov', 'clover', 'json']
+    const reporters = Array.isArray(reporter)
+      ? reporter.map(name => `--reporter=${name}`)
+      : `--reporter=${reporter}`
+
     // should we generate report via NYC module API?
+    const command = 'nyc'
+    const args = ['report', '--report-dir', reportDir].concat(reporters)
+    debug(
+      'saving coverage report using command: "%s %s"',
+      command,
+      args.join(' ')
+    )
     return execa(command, args, { stdio: 'inherit' })
   }
 }