adding a busy waiting for pinging if the mongoDB is ready before finishing the starting of the SUT

Author: jgaleotti

jdk_11_gradle/em/embedded/rest/reservations-api/src/main/java/em/embedded/reservationsapi/EmbeddedEvoMasterController.java

@@ -96,9 +96,34 @@ public String startSut() {
                         "--app.jwt.secret=abcdef012345678901234567890123456789abcdef012345678901234567890123456789"
                 });
 
+        try {
+            Thread.sleep(3_000);
+        } catch (InterruptedException e) {
+            // do nothing
+        }
+
+        while (!isMongoClientReady()) {
+            try {
+                Thread.sleep(1_000);
+            } catch (InterruptedException e) {
+                // do nothing
+            }
+        }
+
         return "http://localhost:" + getSutPort();
     }
 
+    private boolean isMongoClientReady() {
+        try {
+            MongoDatabase db = mongoClient.getDatabase(MONGODB_DATABASE_NAME);
+            Document pingResult = db.runCommand(new Document("ping", 1));
+            return pingResult.getDouble("ok") == 1.0;
+        } catch (Exception ex) {
+            // Connection error
+            return false;
+        }
+    }
+
     protected int getSutPort() {
         return (Integer) ((Map) ctx.getEnvironment()
                 .getPropertySources().get("server.ports").getSource())