Add codecov.io support back thanks to remap-istanbul

- first Jest generates only `coverage-final.json` thanks to `"coverageReporters": ["json"]`
- then remap-istanbul rewrites `coverage-final.json` using the source maps
- and finally `istanbul report` generates `lcov-report` and `lcov.info`

See https://medium.com/@novemberborn/code-coverage-with-babel-istanbul-nyc-83b8c2f1093

.travis.yml

@@ -1,3 +1,8 @@
 language: node_js
 node_js:
   - "7"
+script:
+  - npm run coverage
+after_success:
+  - npm install codecov
+  - codecov

README.md

@@ -4,6 +4,7 @@ Simple form validation for React in [~350 lines of code](src/FormWithConstraints
 
 [![npm version](https://badge.fury.io/js/react-form-with-constraints.svg)](https://badge.fury.io/js/react-form-with-constraints)
 [![Build Status](https://travis-ci.org/tkrotoff/ReactFormWithConstraints.svg?branch=master)](https://travis-ci.org/tkrotoff/ReactFormWithConstraints)
+[![codecov](https://codecov.io/gh/tkrotoff/ReactFormWithConstraints/branch/master/graph/badge.svg)](https://codecov.io/gh/tkrotoff/ReactFormWithConstraints)
 
 - Installation: `npm install react-form-with-constraints`
 - CDN: https://unpkg.com/react-form-with-constraints/dist/react-form-with-constraints.js

package.json

@@ -12,7 +12,7 @@
   "types": "lib/index.d.ts",
 
   "scripts": {
-    "clean": "del-cli build lib dist/*.js",
+    "clean": "del-cli build lib dist/*.js coverage",
 
     "preumd": "tsc",
     "umd": "NODE_ENV=development browserify lib/index.js --external React --external ReactDOM --external PropTypes --standalone ReactFormWithConstraints --outfile dist/react-form-with-constraints.js",
@@ -25,8 +25,15 @@
 
     "pretest": "npm run clean && tsc || true",
     "test": "node --trace-warnings node_modules/.bin/jest --no-cache --verbose",
+
+    "coverage:remap:json": "remap-istanbul --input coverage/coverage-final.json --type json --output coverage/coverage-final.json",
+
     "precoverage": "npm run pretest",
-    "coverage": "node --trace-warnings node_modules/.bin/jest --no-cache --coverage"
+    "coverage": "node --trace-warnings node_modules/.bin/jest --no-cache --coverage && npm run coverage:remap:json && istanbul report"
+  },
+
+  "jest": {
+    "coverageReporters": ["json"]
   },
 
   "dependencies": {
@@ -62,6 +69,7 @@
 
     "jest": "latest",
     "@types/jest": "latest",
+    "remap-istanbul": "latest",
 
     "enzyme": "latest",
     "@types/enzyme": "latest",