MXS-2196: Fix most NPM unit test failures

The REST API and MaxCtrl tests relied upon the implicit sessions that were
created by the listeners. This can be corrected and improved by creating
an actual connection to MaxScale to check that a client session is indeed
created.

server/core/test/rest-api/package.json

@@ -12,6 +12,7 @@
     "ajv": "^5.5.2",
     "chai": "^3.5.0",
     "chai-as-promised": "^6.0.0",
+    "mariadb": "^2.0.1-beta",
     "mocha": "^5.2.0",
     "request": "^2.87.0",
     "request-promise-native": "^1.0.5"

server/core/test/rest-api/test/schema_validation.js

@@ -1,6 +1,20 @@
 // These tests use the server/test/maxscale_test.cnf configuration
 
 require("../utils.js")()
+const mariadb = require('mariadb');
+var conn
+
+function createConnection() {
+    return mariadb.createConnection({host: '127.0.0.1', port: 4006, user: 'maxuser', password: 'maxpwd'})
+        .then(c => {
+            conn = c
+        })
+}
+
+function closeConnection() {
+    conn.end()
+    conn = null
+}
 
 describe("Resource Collections", function() {
     before(startMaxScale)
@@ -36,6 +50,7 @@ describe("Resource Collections", function() {
 
 describe("Individual Resources", function() {
     before(startMaxScale)
+    before(createConnection)
 
     var tests = [
         "/servers/server1",
@@ -63,11 +78,13 @@ describe("Individual Resources", function() {
         });
     })
 
+    after(closeConnection)
     after(stopMaxScale)
 });
 
 describe("Resource Self Links", function() {
     before(startMaxScale)
+    before(createConnection)
 
     var tests = [
         "/servers",
@@ -108,5 +125,6 @@ describe("Resource Self Links", function() {
         });
     })
 
+    after(closeConnection)
     after(stopMaxScale)
 });