From 97df2a506546a04f5f3b46cf0518d314dd9e616f Mon Sep 17 00:00:00 2001
From: Max Gooding <max.gooding@neofinancial.com>
Date: Sat, 17 Oct 2020 16:54:48 -0600
Subject: [PATCH] Warn undefined configs (#13)

---
 CHANGELOG.md                             |  4 ++++
 README.md                                |  7 +++++++
 package.json                             |  2 +-
 src/index.ts                             |  5 +++--
 src/validate-config.ts                   | 16 ++++++++++++++++
 test/fixtures/validate/config.default.ts |  7 +++++++
 test/index.test.ts                       | 11 +++++++++++
 7 files changed, 49 insertions(+), 3 deletions(-)
 create mode 100644 src/validate-config.ts
 create mode 100644 test/fixtures/validate/config.default.ts

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5998663..55127b5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## 1.4.2 (October 17, 2020)
+
+- Warn if a config is undefined, null, 'undefined' or an empty string
+
 ## 1.4.1 (October 17, 2020)
 
 - Better error logging when fetching from Secrets Manager
diff --git a/README.md b/README.md
index 63b0cc0..8bbf5eb 100644
--- a/README.md
+++ b/README.md
@@ -95,6 +95,13 @@ export default {
 
 The default region is `us-east-1` and the default connection timeout is `5000`ms.
 
+Config Dug will warn if it detects invalid config values. Invalid values include:
+
+- undefined
+- null
+- the string 'undefined'
+- an empty string
+
 This package uses the [aws-sdk](https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/) internally. Refer to their documentation for information about [authentication](https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/setting-credentials-node.html), configuring a default [region](https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/setting-region.html) and configuring [access control for AWS Secrets Manager](https://docs.aws.amazon.com/secretsmanager/latest/userguide/auth-and-access.html).
 
 ## Advanced
diff --git a/package.json b/package.json
index edb0961..f4e7123 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "config-dug",
-  "version": "1.4.1",
+  "version": "1.4.2",
   "description": "Config loader with support for AWS Secrets Manager",
   "author": "Neo Financial Engineering <engineering@neofinancial.com>",
   "main": "build/index.js",
diff --git a/src/index.ts b/src/index.ts
index 056c1dd..1af19ac 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -6,10 +6,11 @@ import path from 'path';
 import createDebug from 'debug';
 
 import getSecret from './get-secret';
+import validateConfig from './validate-config';
 
 const debug = createDebug('config-dug');
 
-interface ConfigObject {
+export interface ConfigObject {
   [key: string]: string | boolean | number;
 }
 
@@ -128,7 +129,7 @@ const loadConfig = (configPath = ''): ConfigObject => {
   );
   const config = Object.assign({}, fileConfig, loadSecrets(fileConfig), loadEnvironment());
 
-  return config;
+  return validateConfig(config);
 };
 
 const init = (): ConfigObject => {
diff --git a/src/validate-config.ts b/src/validate-config.ts
new file mode 100644
index 0000000..7912d61
--- /dev/null
+++ b/src/validate-config.ts
@@ -0,0 +1,16 @@
+/* eslint-disable no-console */
+import { ConfigObject } from '.';
+
+const validateConfig = (config: ConfigObject): ConfigObject => {
+  Object.keys(config).forEach(key => {
+    const value = config[key];
+
+    if (value === undefined || value === null || value === 'undefined' || value === '') {
+      console.warn(`WARNING: Found undefined config value for ${key}`);
+    }
+  });
+
+  return config;
+};
+
+export default validateConfig;
diff --git a/test/fixtures/validate/config.default.ts b/test/fixtures/validate/config.default.ts
new file mode 100644
index 0000000..2be1082
--- /dev/null
+++ b/test/fixtures/validate/config.default.ts
@@ -0,0 +1,7 @@
+export default {
+  KEY_1: 'value 1',
+  KEY_2: 0,
+  KEY_3: undefined,
+  KEY_4: 'undefined',
+  KEY_5: ''
+};
diff --git a/test/index.test.ts b/test/index.test.ts
index 650a5a0..6b2f7d9 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -1,3 +1,4 @@
+/* eslint-disable no-console */
 import { loadConfig } from '../src';
 
 test('loading TypeScript config works', (): void => {
@@ -77,3 +78,13 @@ test('loading invalid config does nothing', (): void => {
 
   expect(typeof invalidConfig).toBe('object');
 });
+
+test('config value that is undefined causes a warning', (): void => {
+  jest.spyOn(global.console, 'warn');
+
+  loadConfig('test/fixtures/validate');
+
+  expect(console.warn).toHaveBeenCalledWith('WARNING: Found undefined config value for KEY_3');
+  expect(console.warn).toHaveBeenCalledWith('WARNING: Found undefined config value for KEY_4');
+  expect(console.warn).toHaveBeenCalledWith('WARNING: Found undefined config value for KEY_5');
+});