Prevent removing last struct member in fuzzer test mutations

Signed-off-by: Dennis Potman <dennis@zettascale.tech>

Author: dpotman

tests/support_modules/fuzz_tools/checks/mutated.py

@@ -96,9 +96,6 @@ def check_mutation_key(log: Stream, ctx: FullContext, typename: str, num_samples
     mutated_ctx = FullContext(new_scope)
     mutated_datatype = mutated_ctx.get_datatype(typename)
 
-    if typename == "Zerepainam":
-        print(mutated_ctx.idl_file)
-
     if narrow_ctx.idl_file[1:] == mutated_ctx.idl_file[1:]:
         return True
 

tests/support_modules/fuzz_tools/rand_idl/mutator.py

@@ -102,6 +102,10 @@ def scan_avoid_mutating_field(field: cn.RField):
 def non_valid_mutate_struct(top_scope: cn.RScope, struct: cn.RStruct, random: Random) -> cn.RStruct:
     if struct.extensibility in [cn.RExtensibility.NotSpecified, cn.RExtensibility.Final]:
         action = random.choices([1, 2], weights=[1, 1], k=1)[0]
+
+        if len(struct.fields) == 1:
+            action = 1
+
         if action == 1:
             # add a field
             struct.fields.append(
@@ -119,6 +123,10 @@ def non_valid_mutate_struct(top_scope: cn.RScope, struct: cn.RStruct, random: Ra
             # keyless struct
             action = 1
 
+        # can't remove last field
+        if len(struct.fields) == 1 and action == 2:
+            action = 1
+
         if action == 1:
             # add a field in the middle
             if len(struct.fields) == 0:
@@ -152,7 +160,7 @@ def non_valid_mutate_struct(top_scope: cn.RScope, struct: cn.RStruct, random: Ra
     if struct.extensibility == cn.RExtensibility.Mutable:
         action = random.choices([1, 2], weights=[1, 1], k=1)[0]
 
-        if action == 1 and struct.in_key_path:
+        if action == 1 and struct.in_key_path and len(struct.fields) > 1:
             # remove a key field
             for i, field in enumerate(struct.fields):
                 if 'key' in field.annotations: