add sample products and improve testing for Product

uncloud_vm/models.py

@@ -69,16 +69,6 @@ class VMProduct(Product):
     def recurring_price(self):
         return self.cores * 3 + self.ram_in_gb * 4
 
-    def __str__(self):
-        if self.name:
-            name = f"{self.name} ({self.id})"
-        else:
-            name = self.id
-
-        return "VM {}: {} cores {} gb ram".format(name,
-                                                  self.cores,
-                                                  self.ram_in_gb)
-
     @property
     def description(self):
         return "Virtual machine '{}': {} core(s), {}GB memory".format(
@@ -92,6 +82,17 @@ class VMProduct(Product):
             RecurringPeriod.choices))
 
 
+    def __str__(self):
+        name = f"{self.id}"
+
+        if self.name:
+            name = f"{self.id} ({self.name})"
+
+        return "VM {}: {} cores {} gb ram".format(name,
+                                                  self.cores,
+                                                  self.ram_in_gb)
+
+
 class VMWithOSProduct(VMProduct):
     primary_disk = models.ForeignKey('VMDiskProduct', on_delete=models.CASCADE, null=True)