test: add common.projectDir

Implement common.projectDir which points to the project directory.

PR-URL: #16208
Fixes: nodejs/build#887
Reviewed-By: Vse Mozhet Byt <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Refael Ackermann <[email protected]>

Author: joyeecheung

test/common/README.md

@@ -337,6 +337,11 @@ original state after calling [`common.hijackStdOut()`][].
 
 Path to the 'root' directory. either `/` or `c:\\` (windows)
 
+### projectDir
+* return [<String>]
+
+Path to the project directory.
+
 ### skip(msg)
 * `msg` [<String>]
 

test/common/index.js

@@ -59,6 +59,8 @@ exports.enoughTestCpu = Array.isArray(cpus) &&
                         (cpus.length > 1 || cpus[0].speed > 999);
 
 exports.rootDir = exports.isWindows ? 'c:\\' : '/';
+exports.projectDir = path.resolve(__dirname, '..', '..');
+
 exports.buildType = process.config.target_defaults.default_configuration;
 
 // If env var is set then enable async_hook hooks for all tests.