Added test case for running multiple instances in the same command.

tests/test_ec2/test_instances.py

@@ -1254,3 +1254,18 @@ def test_create_instance_ebs_optimized():
     )
     instance.load()
     instance.ebs_optimized.should.be(False)
+
+@mock_ec2
+def test_run_multiple_instances_in_same_command():
+    instance_count = 4
+    client = boto3.client('ec2', region_name='us-east-1')
+    client.run_instances(ImageId='ami-1234abcd',
+                          MinCount=instance_count,
+                          MaxCount=instance_count)
+    reservations = client.describe_instances()['Reservations']
+
+    reservations[0]['Instances'].should.have.length_of(instance_count)
+
+    instances = reservations[0]['Instances']
+    for i in range(0, instance_count):
+        instances[i]['AmiLaunchIndex'].should.be(i)