test: enforce full coverage

Also, get Windows up to full coverage.

PR-URL: #1598
Credit: @isaacs
Close: #1598
Reviewed-by: @ruyadorno

Author: isaacs

lib/utils/error-message.js

@@ -90,6 +90,7 @@ module.exports = (er) => {
       if (er.file === resolve(npm.prefix, 'package.json')) {
         const { isDiff } = require('parse-conflict-json')
         const txt = require('fs').readFileSync(er.file, 'utf8')
+          .replace(/\r\n/g, '\n')
         if (isDiff(txt)) {
           detail.push([
             '',

package.json

@@ -231,6 +231,7 @@
   "tap": {
     "files": "test/{lib,bin}",
     "coverage-map": "test/coverage-map.js",
+    "check-coverage": true,
     "esm": false,
     "timeout": 600
   },

test/lib/npm.js

@@ -129,6 +129,7 @@ t.test('npm.load', t => {
       ])
       logs.length = 0
 
+      bePosix()
       t.equal(resolve(npm.cache), resolve(CACHE), 'cache is cache')
       const newCache = t.testdir()
       npm.cache = newCache

test/lib/utils/error-message.js

@@ -282,7 +282,7 @@ t.test('json parse', t => {
     process.argv = ['arg', 'v']
     t.matchSnapshot(errorMessage(Object.assign(new Error('not json'), {
       code: 'EJSONPARSE',
-      file: `${dir}/package.json`
+      file: resolve(dir, 'package.json')
     })))
     t.end()
   })