Fallback to process cwd when resolving drive cwd

lib/path.js

@@ -169,10 +169,12 @@ const win32 = {
       } else {
         // Windows has the concept of drive-specific current working
         // directories. If we've resolved a drive letter but not yet an
-        // absolute path, get cwd for that drive. We're sure the device is not
+        // absolute path, get cwd for that drive, or the process cwd if
+        // the drive cwd is not available. We're sure the device is not
         // a UNC path at this points, because UNC paths are always absolute.
-        path = process.env['=' + resolvedDevice];
-        // Verify that a drive-local cwd was found and that it actually points
+        path = process.env['=' + resolvedDevice] || process.cwd();
+
+        // Verify that a cwd was found and that it actually points
         // to our drive. If not, default to the drive's root.
         if (path === undefined ||
             path.slice(0, 3).toLowerCase() !==

test/fixtures/path-resolve.js

@@ -0,0 +1,4 @@
+// Tests resolving a path in the context of a spawned process.
+// See https://github.com/nodejs/node/issues/7215
+var path = require('path');
+console.log(path.resolve(process.argv[2]));

test/parallel/test-path.js

@@ -1,6 +1,7 @@
 'use strict';
 const common = require('../common');
 const assert = require('assert');
+const child = require('child_process');
 const path = require('path');
 
 const f = __filename;
@@ -440,6 +441,17 @@ resolveTests.forEach(function(test) {
 });
 assert.equal(failures.length, 0, failures.join(''));
 
+if (common.isWindows) {
+  // Test resolving the current Windows drive letter from a spawned process.
+  // See https://github.com/nodejs/node/issues/7215
+  const currentDriveLetter = path.parse(process.cwd()).root.substring(0, 2);
+  const resolveFixture = path.join(common.fixturesDir, 'path-resolve.js');
+  var spawnResult = child.spawnSync(
+    process.argv[0], [resolveFixture, currentDriveLetter]);
+  var resolvedPath = spawnResult.stdout.toString().trim();
+  assert.equal(resolvedPath.toLowerCase(), process.cwd().toLowerCase());
+}
+
 
 // path.isAbsolute tests
 assert.equal(path.win32.isAbsolute('/'), true);