Mocking

This Bats helper library provides command mocking functionality for BATS.

It allows to mock commands and check how they were called.

This is a very powerful feature that allows to test complex scenarios as unit tests.

To run multiple mock assertions, check out the step runner helper.

Acknowledgments

This functionality is based on the bats-mock project. A special thank you to the contributors for their original work.

Usage

setup() {
  setup_mock
}

# Example to test the notify.sh script that uses curl to send a notification to external system.
@test "Notify" {
  app_id="9876543210"

  # Mock curl command.
  mock_curl=$(mock_command "curl")

  # Setup mock responses for curl call with specific arguments in notify.sh.
  mock_set_output "${mock_curl}" "12345678910-1234567890-${app_id}-12345" 1
  mock_set_output "${mock_curl}" "201" 2

  run ./notify.sh
  assert_success

  # Single line mock assertion example.
  assert_equal "-s -X GET https://api.example.com/v2/applications.json" "$(mock_get_call_args "${mock_curl}" 1)"
  # Multi-line mock assertion example.
  assert_equal '-X POST https://api.example.com/v2/applications/9876543210/deployments.json -d {
  "deployment": {
    "description": "example description",
  }
}' "$(mock_get_call_args "${mock_curl}" 2)"
}

Setup functions

setup_mock

Setup mock support. Call this function from your test’s setup() method.

mock_command

• Description: Mock provided command.
• Arguments:
  • Mocked command name
• Outputs: Path to created mock file.
• Usage:

  mock_command "ls"
  

mock_set_output

• Description: Sets the output of the mock.
• Arguments:
  • Path to the mock
  • Output or - for STDIN
  • Index of the call (optional)
• Usage:

  mock_set_output ${mock} "some output"
  

mock_set_status

• Description: Sets the exit status of the mock.
• Arguments:
  • Path to the mock
  • Status
  • Index of the call (optional)
• Usage:

  mock_set_status ${mock} 0
  

mock_set_side_effect

• Description: Sets the side effect of the mock.
• Arguments:
  • Path to the mock
  • Side effect or - for STDIN
  • Index of the call (optional)
• Usage:

  mock_set_side_effect ${mock} "some_command"
  

Assertion functions

mock_get_call_args

• Description: Returns the arguments line the mock was called with.
• Arguments:
  • Path to the mock
  • Index of the call (optional)
• Outputs: Arguments line
• Usage:

  assert_equal "expected_arg1 expected_arg2" "$(mock_get_call_args "${mock}" 1)"
  

mock_get_call_num

• Description: Returns the number of times the mock was called.
• Arguments:
  • Path to the mock
• Outputs: Number of calls
• Usage:

  assert_equal "1" "$(mock_get_call_num "${mock}" 1)"
  

mock_get_call_user

• Description: Returns the user the mock was called with.
• Arguments:
  • Path to the mock
  • Index of the call (optional)
• Outputs: User name
• Usage:

  assert_equal "expected_user" "$(mock_get_call_user "${mock}" VAR_NAME 1)"
  

mock_get_call_env

• Description: Returns the value of the environment variable the mock was called with.
• Arguments:
  • Path to the mock
  • Variable name
  • Index of the call (optional)
• Outputs: Variable value
• Usage:

  assert_equal "expected_val1" "$(mock_get_call_env "${mock}" VAR_NAME 1)"