old_contents: import pytest
  from conftest import (POSITIVE_HOST_PATTERNS, NEGATIVE_HOST_PATTERNS)
  
  
  @pytest.mark.parametrize("host_pattern, num_hosts", POSITIVE_HOST_PATTERNS)
  def test_len(host_pattern, num_hosts, hosts):
      assert len(getattr(hosts, host_pattern)) == num_hosts
  
  
  @pytest.mark.parametrize("host_pattern, num_hosts", POSITIVE_HOST_PATTERNS)
  def test_contains(host_pattern, num_hosts, hosts):
      assert host_pattern in hosts.all
      assert host_pattern in hosts['all']
  
  
  @pytest.mark.parametrize("host_pattern, num_hosts", NEGATIVE_HOST_PATTERNS)
  def test_not_contains(host_pattern, num_hosts, hosts):
      assert host_pattern not in hosts.all
      assert host_pattern not in hosts['all']
  
  
  def test_ansible_module_error(hosts):
      '''Verify that AnsibleModuleError is raised when no such module exists.'''
      from pytest_ansible.errors import AnsibleModuleError
      with pytest.raises(AnsibleModuleError):
          # The following allows us to introspect the exception object
          try:
              hosts.all.a_module_that_most_certainly_does_not_exist()
          except AnsibleModuleError, e:
              assert e.message == "The module {0} was not found in configured module paths.".format("a_module_that_most_certainly_does_not_exist")
              raise
          else:
              pytest.fail("pytest_ansible.errors.AnsibleModuleError was not raised as expected")
  
new_contents: import pytest
  from conftest import (POSITIVE_HOST_PATTERNS, NEGATIVE_HOST_PATTERNS)
  
  
  @pytest.mark.parametrize("host_pattern, num_hosts", POSITIVE_HOST_PATTERNS)
  def test_len(host_pattern, num_hosts, hosts):
      assert len(getattr(hosts, host_pattern)) == num_hosts
  
  
  @pytest.mark.parametrize("host_pattern, num_hosts", POSITIVE_HOST_PATTERNS)
  def test_contains(host_pattern, num_hosts, hosts):
      assert host_pattern in hosts.all
      assert host_pattern in hosts['all']
  
  
  @pytest.mark.parametrize("host_pattern, num_hosts", NEGATIVE_HOST_PATTERNS)
  def test_not_contains(host_pattern, num_hosts, hosts):
      assert host_pattern not in hosts.all
      assert host_pattern not in hosts['all']
  
  
  def test_ansible_module_error(hosts):
      '''Verify that AnsibleModuleError is raised when no such module exists.'''
      from pytest_ansible.errors import AnsibleModuleError
      with pytest.raises(AnsibleModuleError) as exc_info:
          hosts.all.a_module_that_most_certainly_does_not_exist()
      assert str(exc_info.value) == "The module {0} was not found in configured module paths.".format("a_module_that_most_certainly_does_not_exist")
  
subject: Use more prefered exc_info inspection technique