module: check env NODE_REQUIRE for preload modules

Adds a new feature that checks the environment variable NODE_REQUIRE
that should be a : (or ; on windows) delimited string of modules to
preload, the same as those that can be specified by the -r command
line option. 

Implements: #11853

Author: jchip

lib/internal/bootstrap_node.js

@@ -394,8 +394,15 @@
 
   // Load preload modules
   function preloadModules() {
-    if (process._preload_modules) {
-      NativeModule.require('module')._preloadModules(process._preload_modules);
+    let preloads = process._preload_modules;
+
+    if (process.env.NODE_REQUIRE) {
+      const d = NativeModule.require('path').delimiter;
+      preloads = (preloads || []).concat(process.env.NODE_REQUIRE.split(d));
+    }
+
+    if (preloads) {
+      NativeModule.require('module')._preloadModules(preloads);
     }
   }
 

test/parallel/test-preload.js

@@ -146,3 +146,46 @@ childProcess.exec(
     assert.ok(/worker terminated with code 43/.test(stdout));
   }
 );
+
+// test NODE_REQUIRE with a single module works
+process.env.NODE_REQUIRE = fixtureA;
+childProcess.exec(nodeBinary + ' ' + fixtureB,
+                  function(err, stdout, stderr) {
+                    assert.ifError(err);
+                    assert.strictEqual(stdout, 'A\nB\n');
+                  });
+
+// test NODE_REQUIRE with multiple modules works
+process.env.NODE_REQUIRE = fixtureA + path.delimiter + fixtureB;
+childProcess.exec(
+  nodeBinary + ' ' + fixtureC,
+  function(err, stdout, stderr) {
+    assert.ifError(err);
+    assert.strictEqual(stdout, 'A\nB\nC\n');
+  }
+);
+
+// test NODE_REQUIRE with a throwing module aborts
+process.env.NODE_REQUIRE = fixtureA + path.delimiter + fixtureThrows;
+childProcess.exec(
+  nodeBinary + ' ' + fixtureB,
+  function(err, stdout, stderr) {
+    if (err) {
+      assert.strictEqual(stdout, 'A\n');
+    } else {
+      throw new Error('NODE_REQUIRE Preload should have failed');
+    }
+  }
+);
+
+// test mixing NODE_REQUIRE with -r works
+process.env.NODE_REQUIRE = fixtureB;
+childProcess.exec(
+  nodeBinary + ' ' + preloadOption([fixtureA]) + ' ' + fixtureC,
+  function(err, stdout, stderr) {
+    assert.ifError(err);
+    assert.strictEqual(stdout, 'A\nB\nC\n');
+  }
+);
+
+delete process.env.NODE_REQUIRE;