Mock Testing with DevCycle

Mock testing allows you to test your application's behavior with specific Feature and Variable configurations without making API calls to DevCycle. This enables faster, more reliable tests that don't depend on external services.

Mock Testing Strategy

The general testing strategy we'd recommend is to mock DevCycle's Variable and Variable value calls as opposed to mocking the full DevCycle client. To achieve this, you'd want to perform network level mocking to intercept the Variables or Variable by key requests to provide your own Variable response.

Server-Side SDKs: Cloud Bucketing

DevCycle's Server-side SDKs can operate on Cloud or Local Bucketing modes. We'd recommend using Cloud Bucketing for mock testing. Cloud Bucketing uses the DevCycle Bucketing API behind the scenes to fetch and retrive Variable values. You may mock the response of the Get Variable by Key or Get Variables endpoints in order to replicate the output of your Server-side SDK.

Setup

The SDK Key does not need to be a valid SDK key, but it needs to be in a correctly formatted starting with dvc_server or server.

Python (unittest)

def setUp(self):
  self.sdk_key = "dvc_server_test_key_12345678"
  self.bucketing_api_base = "https://bucketing-api.devcycle.com"
  self.options = DevCycleCloudOptions(
    bucketing_api_uri=self.bucketing_api_base,
    request_timeout=5,
    request_retries=0,
  )
  self.client = DevCycleCloudClient(self.sdk_key, self.options)

def tearDown(self):
  if self.client:
    self.client.close()
  responses.reset()

def _get_variable_url(self, key: str) -> str:
  """Get the URL for a single variable request"""
  return f"{self.bucketing_api_base}/v1/variables/{key}"

def _get_variables_url(self) -> str:
  """Get the URL for all variables request"""
  return f"{self.bucketing_api_base}/v1/variables"

Variable and VariableValue Test

Test retrieving a Variable value through the .variable() or .variableValue() method.

Python (unittest)

def test_variable_value_string(self):
  """Test variable_value() with a string variable"""
  variable_key = "string-test-var"
  expected_value = "var-on"
  
  responses.add(
    responses.POST,
    self._get_variable_url(variable_key),
    json={
      "_id": "12345",
      "key": variable_key,
      "type": "String",
      "value": expected_value,
      "eval": {
        "reason": "TARGETING_MATCH",
        "details": "All Users",
        "target_id": "54321"
      }
    },
    status=200,
  )

  user = DevCycleUser(user_id="test-user-123")
  result = self.client.variable_value(user, variable_key, "default-value")

  self.assertEqual(result, expected_value)
  # Verify the request was made
  self.assertEqual(len(responses.calls), 1)
  self.assertEqual(responses.calls[0].request.method, "POST")

AllVariables Test

Test retrieving all active Variables through the .allVariable() method.

Python (unittest)

def test_all_variables(self):
  """Test retrieving all variables using all_variables()"""
  responses.add(
    responses.POST,
    self._get_variables_url(),
    json={
      "string-test-var": {
        "_id": "123456",
        "key": "string-test-var",
        "type": "String",
        "value": "var-on",
        "eval": {
          "reason": "TARGETING_MATCH",
          "details": "All Users",
          "target_id": "654321"
        }
      },
      "bool-test-var": {
        "_id": "123456",
        "key": "bool-test-var",
        "type": "Boolean",
        "value": True,
        "eval": {
          "reason": "TARGETING_MATCH",
          "details": "All Users",
          "target_id": "654321"
        }
      }
    },
    status=200,
  )

  user = DevCycleUser(user_id="test-user-123")
  result = self.client.all_variables(user)

  # Verify the response structure
  self.assertIsInstance(result, dict)
  self.assertIn("string-test-var", result)
  self.assertIn("bool-test-var", result)
  
  # Verify variable values
  self.assertEqual(result["string-test-var"].value, "var-on")
  self.assertEqual(result["string-test-var"].key, "string-test-var")
  self.assertEqual(result["string-test-var"].type, "String")
  
  self.assertTrue(result["bool-test-var"].value)
  self.assertEqual(result["bool-test-var"].key, "bool-test-var")
  self.assertEqual(result["bool-test-var"].type, "Boolean")
  
  # Verify the request was made to the correct URL
  self.assertEqual(len(responses.calls), 1)
  self.assertEqual(responses.calls[0].request.method, "POST")
  self.assertEqual(responses.calls[0].request.url, self._get_variables_url())

Client-Side SDKs: Bootstrapping

Client-side Web SDKs (JavaScript, React, Next.js) support bootstrapping, which allows you to pass a pre-configured DevCycle configuration during initialization.

const bootstrapConfig = {
  // Your test configuration here
}

const devcycleClient = initializeDevCycle(
  '<DEVCYCLE_CLIENT_SDK_KEY>',
  user,
  { bootstrapConfig }
)

Best Practices

• Use consistent test configurations across your test suite
• Test both enabled and disabled states of Features
• Test Variables and Variations to ensure all code paths are covered
• Keep mock configurations close to your test files for easy maintenance