test: remove common.fixturesDir from tests

Use common/fixtures module instead of common.fixturesDir.

PR-URL: #17400
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Lance Ball <lball@redhat.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

test/parallel/test-tls-interleave.js

@@ -26,15 +26,13 @@ if (!common.hasCrypto)
   common.skip('missing crypto');
 
 const assert = require('assert');
-
 const tls = require('tls');
 
-const fs = require('fs');
+const fixtures = require('../common/fixtures');
 
-const dir = common.fixturesDir;
-const options = { key: fs.readFileSync(`${dir}/test_key.pem`),
-                  cert: fs.readFileSync(`${dir}/test_cert.pem`),
-                  ca: [ fs.readFileSync(`${dir}/test_ca.pem`) ] };
+const options = { key: fixtures.readSync('test_key.pem'),
+                  cert: fixtures.readSync('test_cert.pem'),
+                  ca: [ fixtures.readSync('test_ca.pem') ] };
 
 const writes = [
   'some server data',

test/parallel/test-tls-invoke-queued.js

@@ -26,14 +26,15 @@ if (!common.hasCrypto)
   common.skip('missing crypto');
 
 const assert = require('assert');
-const fs = require('fs');
 const tls = require('tls');
 
+const fixtures = require('../common/fixtures');
+
 let received = '';
 
 const server = tls.createServer({
-  key: fs.readFileSync(`${common.fixturesDir}/keys/agent1-key.pem`),
-  cert: fs.readFileSync(`${common.fixturesDir}/keys/agent1-cert.pem`)
+  key: fixtures.readKey('agent1-key.pem'),
+  cert: fixtures.readKey('agent1-cert.pem')
 }, common.mustCall(function(c) {
   c._write('hello ', null, common.mustCall(function() {
     c._write('world!', null, common.mustCall(function() {