Add tests for ard level serology mapping

Author: pbashyal-nmdp

tests/features/serology_redux.feature

@@ -29,3 +29,11 @@ Feature: Serology Reduction
     Examples:  Skip Loci that don't have Serology mappings
       | Allele                                                                          | Level | Redux Serology      |
       | A*01:01+A*01:01^B*08:ASXJP+B*07:02^C*02:02+C*07:HTGM^DPB1*28:01:01G+DPB1*296:01 | S     | A1+A1^B7+B8^Cw2+Cw7 |
+
+    Examples: 2 field Serology Reduction uses lgx version of serology mapping
+
+      | Allele        | Level | Redux Serology |
+      | DRB1*07:34    | S     | DR7            |
+      | DRB1*07:34:01 | S     | DR7            |
+      | DRB1*07:34:02 | S     | DR7            |
+      | DRB4*01:03N   | S     | X              |

tests/steps/redux_allele.py

@@ -39,7 +39,11 @@ def step_impl(context, level):
 @when("reducing on the {level} level with ping")
 def step_impl(context, level):
     context.level = level
-    context.redux_allele = context.ard_ping.redux(context.allele, level)
+    redux_allele = context.ard_ping.redux(context.allele, level)
+    if not redux_allele:
+        context.redux_allele = "X"
+    else:
+        context.redux_allele = redux_allele
 
 
 @when("reducing on the {level} level with ARS suffix enabled")