From c18fb0a9a8eae5904298d87c62d9934243de8674 Mon Sep 17 00:00:00 2001
From: Corey Farrell <git@cfware.com>
Date: Tue, 24 Sep 2019 13:36:49 -0400
Subject: [PATCH] fix: Honor eager setting (false by default) (#1179)

This delays loading of istanbul-lib-instrument until it is needed.
---
 lib/instrumenters/istanbul.js           |  9 ++++----
 lib/instrumenters/noop.js               |  4 +++-
 tap-snapshots/test-eager.js-TAP.test.js | 16 +++++++++++++
 test/eager.js                           | 30 +++++++++++++++++++++++++
 test/fixtures/eager.js                  |  5 +++++
 5 files changed, 59 insertions(+), 5 deletions(-)
 create mode 100644 tap-snapshots/test-eager.js-TAP.test.js
 create mode 100644 test/eager.js
 create mode 100644 test/fixtures/eager.js

diff --git a/lib/instrumenters/istanbul.js b/lib/instrumenters/istanbul.js
index a10c7d1ba..29462181b 100644
--- a/lib/instrumenters/istanbul.js
+++ b/lib/instrumenters/istanbul.js
@@ -1,10 +1,10 @@
 'use strict'
 
-const { createInstrumenter } = require('istanbul-lib-instrument')
-const convertSourceMap = require('convert-source-map')
-const mergeSourceMap = require('merge-source-map')
-
 function InstrumenterIstanbul (options) {
+  const { createInstrumenter } = require('istanbul-lib-instrument')
+  const convertSourceMap = require('convert-source-map')
+  const mergeSourceMap = require('merge-source-map')
+
   const { plugins } = options
   const configPlugins = plugins ? { plugins } : {}
 
@@ -28,6 +28,7 @@ function InstrumenterIstanbul (options) {
       // TODO: test source-map merging logic.
       if (options.produceSourceMap) {
         var lastSourceMap = instrumenter.lastSourceMap()
+        /* istanbul ignore else */
         if (lastSourceMap) {
           if (sourceMap) {
             lastSourceMap = mergeSourceMap(
diff --git a/lib/instrumenters/noop.js b/lib/instrumenters/noop.js
index 7efe8bd80..b0c9f70f9 100644
--- a/lib/instrumenters/noop.js
+++ b/lib/instrumenters/noop.js
@@ -1,6 +1,8 @@
-const { readInitialCoverage } = require('istanbul-lib-instrument')
+'use strict'
 
 function NOOP () {
+  const { readInitialCoverage } = require('istanbul-lib-instrument')
+
   return {
     instrumentSync (code, filename) {
       const extracted = readInitialCoverage(code)
diff --git a/tap-snapshots/test-eager.js-TAP.test.js b/tap-snapshots/test-eager.js-TAP.test.js
new file mode 100644
index 000000000..7949315f1
--- /dev/null
+++ b/tap-snapshots/test-eager.js-TAP.test.js
@@ -0,0 +1,16 @@
+/* IMPORTANT
+ * This snapshot file is auto-generated, but designed for humans.
+ * It should be checked into source control and tracked carefully.
+ * Re-generate by setting TAP_SNAPSHOT=1 and running tests.
+ * Make sure to inspect the output below.  Do not ignore changes!
+ */
+'use strict'
+exports[`test/eager.js TAP eager disabled by default > stdout 1`] = `
+0
+
+`
+
+exports[`test/eager.js TAP eager enabled > stdout 1`] = `
+1
+
+`
diff --git a/test/eager.js b/test/eager.js
new file mode 100644
index 000000000..14ccddb7e
--- /dev/null
+++ b/test/eager.js
@@ -0,0 +1,30 @@
+'use strict'
+
+const path = require('path')
+
+const t = require('tap')
+
+const { testSuccess } = require('./helpers')
+
+const cwd = path.resolve(__dirname, 'fixtures')
+
+t.test('eager disabled by default', t => testSuccess(t, {
+  args: [
+    '--silent=true',
+    '--exclude=eager.js',
+    process.execPath,
+    './eager.js'
+  ],
+  cwd
+}))
+
+t.test('eager enabled', t => testSuccess(t, {
+  args: [
+    '--silent=true',
+    '--eager=true',
+    '--exclude=eager.js',
+    process.execPath,
+    './eager.js'
+  ],
+  cwd
+}))
diff --git a/test/fixtures/eager.js b/test/fixtures/eager.js
new file mode 100644
index 000000000..473b9ff56
--- /dev/null
+++ b/test/fixtures/eager.js
@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+'use strict'
+
+const lib = require.resolve('istanbul-lib-instrument')
+console.log(Object.keys(require.cache).filter(s => s === lib).length)