fixed minor bug

moto/elbv2/models.py

@@ -1378,8 +1378,6 @@ def describe_target_groups(
                 "Target group names, target group ARNs, and a load balancer ARN cannot be specified at the same time"
             )
 
-        target_groups = []
-
         if load_balancer_arn:
             if load_balancer_arn not in self.load_balancers:
                 raise LoadBalancerNotFoundError()
@@ -1388,25 +1386,30 @@ def describe_target_groups(
                 for tg in self.target_groups.values()
                 if load_balancer_arn in tg.load_balancer_arns
             ]
+            if target_groups is None or len(target_groups) == 0:
+                raise TargetGroupNotFoundError()
+            return sorted(target_groups, key=lambda tg: tg.name)
 
         if target_group_arns:
             try:
                 target_groups = [self.target_groups[arn] for arn in target_group_arns]
+                return sorted(target_groups, key=lambda tg: tg.name)
             except KeyError:
                 raise TargetGroupNotFoundError()
 
         if names:
-            target_groups = [
-                next((tg for tg in self.target_groups.values() if tg.name == name))
-                for name in names
-            ]
-            if None in target_groups:
-                raise TargetGroupNotFoundError()
-
-        if len(target_groups) == 0:
-            target_groups = list(self.target_groups.values())
-
-        return sorted(target_groups, key=lambda tg: tg.name)
+            matched = []
+            for name in names:
+                found = None
+                for target_group in self.target_groups.values():
+                    if target_group.name == name:
+                        found = target_group
+                if not found:
+                    raise TargetGroupNotFoundError()
+                matched.append(found)
+            return sorted(matched, key=lambda tg: tg.name)
+
+        return sorted(self.target_groups.values(), key=lambda tg: tg.name)
 
     def describe_listeners(
         self, load_balancer_arn: Optional[str], listener_arns: List[str]

tests/test_elbv2/test_elbv2_target_groups.py

@@ -122,7 +122,7 @@ def test_create_target_group_and_listeners():
     http_listener_arn = listener["ListenerArn"]
 
     response = conn.describe_target_groups(
-        LoadBalancerArn=load_balancer_arn, Names=["a-target"]
+        LoadBalancerArn=load_balancer_arn,
     )
     assert len(response["TargetGroups"]) == 1
 
@@ -455,7 +455,7 @@ def test_describe_invalid_target_group():
         conn.describe_target_groups(Names=["invalid"])
     err = exc.value.response["Error"]
     assert err["Code"] == "TargetGroupNotFound"
-    assert err["Message"] == "The specified target group does not exist."
+    assert err["Message"] == "One or more target groups not found"
 
 
 @mock_elbv2
@@ -471,7 +471,7 @@ def test_describe_target_groups():
     groups = conn.describe_target_groups()["TargetGroups"]
     assert len(groups) == 0
 
-    conn.create_target_group(
+    response = conn.create_target_group(
         Name="a-target",
         Protocol="HTTP",
         Port=8080,
@@ -485,6 +485,14 @@ def test_describe_target_groups():
         UnhealthyThresholdCount=2,
         Matcher={"HttpCode": "201"},
     )
+    arn_a = response["TargetGroups"][0]["TargetGroupArn"]
+
+    conn.create_listener(
+        LoadBalancerArn=lb_arn,
+        Protocol="HTTP",
+        Port=80,
+        DefaultActions=[{"Type": "forward", "TargetGroupArn": arn_a}],
+    )
 
     groups = conn.describe_target_groups()["TargetGroups"]
     assert len(groups) == 1
@@ -537,12 +545,19 @@ def test_describe_target_groups():
     assert len(groups) == 1
     assert groups[0]["TargetGroupName"] == "a-target"
 
-    conn.create_target_group(
+    response = conn.create_target_group(
         Name="d-target",
         Protocol="HTTP",
         Port=8082,
         VpcId=vpc.id,
     )
+    arn_d = response["TargetGroups"][0]["TargetGroupArn"]
+    conn.create_listener(
+        LoadBalancerArn=lb_arn,
+        Protocol="HTTP",
+        Port=80,
+        DefaultActions=[{"Type": "forward", "TargetGroupArn": arn_d}],
+    )
     groups = conn.describe_target_groups(LoadBalancerArn=lb_arn)["TargetGroups"]
     assert len(groups) == 2
     assert groups[0]["TargetGroupName"] == "a-target"