Rewrite custom require hook & source map tests

package.json

@@ -15,7 +15,10 @@
       "exclude": [
         "node_modules",
         "bin",
-        "coverage"
+        "coverage",
+        "test/nyc-test.js",
+        "test/source-map-cache.js",
+        "test/fixtures/_generateCoverage.js"
       ]
     }
   },
@@ -57,10 +60,9 @@
     "yargs": "^3.15.0"
   },
   "devDependencies": {
-    "babel-core": "^6.2.1",
-    "babel-preset-es2015": "^6.1.18",
     "chai": "^3.0.0",
     "sinon": "^1.15.3",
+    "source-map-fixtures": "^0.1.0",
     "standard": "^5.2.1",
     "tap": "^1.3.4"
   },

test/fixtures/_generateCoverage.js

@@ -0,0 +1,48 @@
+'use strict'
+
+// Generates the test/fixtures/coverage.js file, not otherwise used in the
+// tests.
+
+var fs = require('fs')
+var path = require('path')
+
+var _ = require('lodash')
+var rimraf = require('rimraf')
+
+var NYC = require('../../')
+
+// Load the 'branching' source map fixture.
+var fixture = require('source-map-fixtures').inline('branching')
+
+// Prevent pollution from earlier nyc runs.
+var tempDirectory = path.join(__dirname, '.nyc_output')
+rimraf.sync(tempDirectory)
+
+// Inject nyc into this process.
+var nyc = (new NYC({
+  cwd: path.join(__dirname, '..', '..'),
+  tempDirectory: tempDirectory
+})).wrap()
+// Override the exclude option, source-map-fixtures is inside node_modules but
+// should not be excluded when generating the coverage report.
+nyc.exclude = []
+
+// Require the fixture so nyc can instrument it, then run it so there's code
+// coverage.
+fixture.require().run()
+
+// Write the coverage file so reports can be loaded.
+nyc.writeCoverageFile()
+
+var reports = _.values(nyc._loadReports()[0])
+if (reports.length !== 1) {
+  console.error('Expected 1 report to be generated, got ' + reports.length)
+  process.exit(1)
+}
+
+var coverage = reports[0]
+fs.writeFileSync(
+  path.join(__dirname, 'coverage.js'),
+  '// Generated using node test/fixtures/_generateCoverage.js\n' +
+  'exports[' + JSON.stringify(coverage.path) + '] = ' + JSON.stringify(coverage, null, 2) + '\n')
+console.log('Written coverage report.')