tests(parameters): integration tests for AppConfigProvider (#1287)

* tests: appconfigprovider e2e tests

* tests: completed e2e tests

* chore: added effect in policy

* chore: add missing semicolon

* chore: fix indentation

* chore: documented explicit dependency

Author: dreamorosi

Diff for: packages/parameters/tests/e2e/appConfigProvider.class.test.functionCode.ts

@@ -0,0 +1,118 @@
+import { Context } from 'aws-lambda';
+import {
+  AppConfigProvider,
+} from '../../src/appconfig';
+import {
+  AppConfigGetOptionsInterface,
+} from '../../src/types';
+import { TinyLogger } from '../helpers/tinyLogger';
+import { middleware } from '../helpers/sdkMiddlewareRequestCounter';
+import { AppConfigDataClient } from '@aws-sdk/client-appconfigdata';
+
+// We use a custom logger to log pure JSON objects to stdout
+const logger = new TinyLogger();
+
+const application = process.env.APPLICATION_NAME || 'my-app';
+const environment = process.env.ENVIRONMENT_NAME || 'my-env';
+const freeFormJsonName = process.env.FREEFORM_JSON_NAME || 'freeform-json';
+const freeFormYamlName = process.env.FREEFORM_YAML_NAME || 'freeform-yaml';
+const freeFormPlainTextNameA = process.env.FREEFORM_PLAIN_TEXT_NAME_A || 'freeform-plain-text';
+const freeFormPlainTextNameB = process.env.FREEFORM_PLAIN_TEXT_NAME_B || 'freeform-plain-text';
+const featureFlagName = process.env.FEATURE_FLAG_NAME || 'feature-flag';
+
+const defaultProvider = new AppConfigProvider({
+  application,
+  environment,
+});
+// Provider test 
+const customClient = new AppConfigDataClient({});
+customClient.middlewareStack.use(middleware);
+const providerWithMiddleware = new AppConfigProvider({
+  awsSdkV3Client: customClient,
+  application,
+  environment,
+});
+
+// Use provider specified, or default to main one & return it with cache cleared
+const resolveProvider = (provider?: AppConfigProvider): AppConfigProvider => {
+  const resolvedProvider = provider ? provider : defaultProvider;
+  resolvedProvider.clearCache();
+
+  return resolvedProvider;
+};
+
+// Helper function to call get() and log the result
+const _call_get = async (
+  paramName: string,
+  testName: string,
+  options?: AppConfigGetOptionsInterface,
+  provider?: AppConfigProvider,
+): Promise<void> => {
+  try {
+    const currentProvider = resolveProvider(provider);
+
+    const parameterValue = await currentProvider.get(paramName, options);
+    logger.log({
+      test: testName,
+      value: parameterValue
+    });
+  } catch (err) {
+    logger.log({
+      test: testName,
+      error: err.message
+    });
+  }
+};
+
+export const handler = async (_event: unknown, _context: Context): Promise<void> => {
+  // Test 1 - get a single parameter as-is (no transformation)
+  await _call_get(freeFormPlainTextNameA, 'get');
+
+  // Test 2 - get a free-form JSON and apply binary transformation (should return a stringified JSON)
+  await _call_get(freeFormJsonName, 'get-freeform-json-binary', { transform: 'binary' });
+
+  // Test 3 - get a free-form YAML and apply binary transformation (should return a string-encoded YAML)
+  await _call_get(freeFormYamlName, 'get-freeform-yaml-binary', { transform: 'binary' });
+
+  // Test 4 - get a free-form plain text and apply binary transformation (should return a string)
+  await _call_get(freeFormPlainTextNameB, 'get-freeform-plain-text-binary', { transform: 'binary' });
+
+  // Test 5 - get a feature flag and apply binary transformation (should return a stringified JSON)
+  await _call_get(featureFlagName, 'get-feature-flag-binary', { transform: 'binary' });
+
+  // Test 6
+  // get parameter twice with middleware, which counts the number of requests, we check later if we only called AppConfig API once
+  try {
+    providerWithMiddleware.clearCache();
+    middleware.counter = 0;
+    await providerWithMiddleware.get(freeFormPlainTextNameA);
+    await providerWithMiddleware.get(freeFormPlainTextNameA);
+    logger.log({
+      test: 'get-cached',
+      value: middleware.counter // should be 1
+    });
+  } catch (err) {
+    logger.log({
+      test: 'get-cached',
+      error: err.message
+    });
+  }
+
+  // Test 7
+  // get parameter twice, but force fetch 2nd time, we count number of SDK requests and check that we made two API calls
+  try {
+    providerWithMiddleware.clearCache();
+    middleware.counter = 0;
+    await providerWithMiddleware.get(freeFormPlainTextNameA);
+    await providerWithMiddleware.get(freeFormPlainTextNameA, { forceFetch: true });
+    logger.log({
+      test: 'get-forced',
+      value: middleware.counter // should be 2
+    });
+  } catch (err) {
+    logger.log({
+      test: 'get-forced',
+      error: err.message
+    });
+  }
+};