n-api: expose n-api version in process.versions

Expose n-api version in process.versions so that it is
available for use in javascript by external modules
like node-pre-gyp. It was previously accessible through
a functon available in the N-API.

Backport-PR-URL: #19447
PR-URL: #18067
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Tobias Nießn <tniessen@tnie.de>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

Author: mhdawson

src/node.cc

@@ -3198,6 +3198,12 @@ void SetupProcessObject(Environment* env,
       "modules",
       FIXED_ONE_BYTE_STRING(env->isolate(), node_modules_version));
 
+  const char node_napi_version[] = NODE_STRINGIFY(NAPI_VERSION);
+  READONLY_PROPERTY(
+      versions,
+      "napi",
+      FIXED_ONE_BYTE_STRING(env->isolate(), node_napi_version));
+
   // process._promiseRejectEvent
   Local<Object> promiseRejectEvent = Object::New(env->isolate());
   READONLY_DONT_ENUM_PROPERTY(process,

src/node_api.cc

@@ -22,8 +22,6 @@
 #include "node_api_backport.h"
 #include "util.h"
 
-#define NAPI_VERSION  2
-
 static
 napi_status napi_set_last_error(napi_env env, napi_status error_code,
                                 uint32_t engine_error_code = 0,

src/node_version.h

@@ -61,4 +61,7 @@
  */
 #define NODE_MODULE_VERSION 48 /* Node.js v6.0.0 */
 
+// the NAPI_VERSION provided by this version of the runtime
+#define NAPI_VERSION  2
+
 #endif  // SRC_NODE_VERSION_H_

test/parallel/test-process-versions.js

@@ -3,7 +3,7 @@ const common = require('../common');
 const assert = require('assert');
 
 const expected_keys = ['ares', 'http_parser', 'modules', 'node',
-                       'uv', 'v8', 'zlib'];
+                       'uv', 'v8', 'zlib', 'napi'];
 
 if (common.hasCrypto) {
   expected_keys.push('openssl');