getConfig: update to have failOnNotFound option to fail on compiler

Author: clairep94

client/utils/getConfig.test.ts

@@ -27,18 +27,55 @@ describe('utils/getConfig()', () => {
   });
 
   // check returns unhappy path
-  it('warns but does not throw if no value found', () => {
-    expect(() => getConfig('CONFIG_TEST_KEY_NAME')).not.toThrow();
-  });
+  describe('and when the key does not exist in the env file', () => {
+    it('warns but does not throw if failOnNotFound is false (default)', () => {
+      expect(() => getConfig('CONFIG_TEST_KEY_NAME')).not.toThrow();
+    });
+
+    it('throws an error if failOnNotFound is true', () => {
+      expect(() =>
+        getConfig('CONFIG_TEST_KEY_NAME', { failOnNotFound: true })
+      ).toThrow();
+    });
 
-  it('returns the expected nullish value when no value is found', () => {
-    const result = getConfig('CONFIG_TEST_KEY_NAME');
-    expect(result).toBe(undefined);
-    expect(!result).toBe(true);
-    expect(`${result}`).toBe('undefined');
+    it('returns undefined by default', () => {
+      const result = getConfig('CONFIG_TEST_KEY_NAME');
+      expect(result).toBe(undefined);
+      expect(!result).toBe(true);
+      expect(`${result}`).toBe('undefined');
+    });
+
+    it('can be set to return an empty string as the nullish value', () => {
+      const result = getConfig('CONFIG_TEST_KEY_NAME', { nullishString: true });
+      expect(`${result}`).toBe('');
+    });
   });
-  it('can be set to return an empty string as the nullish value', () => {
-    const result = getConfig('CONFIG_TEST_KEY_NAME', { nullishString: true });
-    expect(`${result}`).toBe('');
+
+  describe('and when the key exists in the env file but the value is empty', () => {
+    beforeEach(() => {
+      global.process.env.CONFIG_TEST_KEY_NAME = '';
+    });
+
+    it('warns but does not throw if failOnNotFound is false (default)', () => {
+      expect(() => getConfig('CONFIG_TEST_KEY_NAME')).not.toThrow();
+    });
+
+    it('throws an error if failOnNotFound is true', () => {
+      expect(() =>
+        getConfig('CONFIG_TEST_KEY_NAME', { failOnNotFound: true })
+      ).toThrow();
+    });
+
+    it('returns undefined by default', () => {
+      const result = getConfig('CONFIG_TEST_KEY_NAME');
+      expect(result).toBe(undefined);
+      expect(!result).toBe(true);
+      expect(`${result}`).toBe('undefined');
+    });
+
+    it('can be set to return an empty string as the nullish value', () => {
+      const result = getConfig('CONFIG_TEST_KEY_NAME', { nullishString: true });
+      expect(`${result}`).toBe('');
+    });
   });
 });

client/utils/getConfig.ts

@@ -3,23 +3,33 @@
  * @returns String value of env variable or undefined if not found.
  */
 function getEnvVar(key: string): string | undefined {
-  const env: Record<string, string | undefined> =
-    (typeof global !== 'undefined' ? global : window)?.process?.env || {};
+  const configSource = global ?? window;
+  const env = configSource?.process?.env ?? {};
 
   return env[key];
 }
 
-type GetConfigOptions = {
+interface GetConfigOptions {
   warn?: boolean;
   nullishString?: boolean;
+  failOnNotFound?: boolean;
+}
+
+const isTestEnvironment = getEnvVar('NODE_ENV') === 'test';
+
+const defaultGetConfigOptions: GetConfigOptions = {
+  warn: !isTestEnvironment,
+  nullishString: false,
+  failOnNotFound: false
 };
 
 /**
  * Returns a string config value from environment variables.
- * Logs a warning if the value is missing and `warn` is not explicitly disabled.
+ * Logs a warning or throws an error if the value is missing, if `warn` and `failOnNotFound` are true in options
  *
  * @param key - The environment variable key to fetch.
  * @param options - Optional settings:
+ *   - `failOnNotFound`: whether to throw an error if the value is missing (default to `false`).
  *   - `warn`: whether to warn if the value is missing (default `true` unless in test env).
  *   - `nullishString`: if true, returns `''` instead of `undefined` when missing.
  * @returns String value of the env var, or `''` or `undefined` if missing.
@@ -31,15 +41,26 @@ export function getConfig(
   if (!key) {
     throw new Error('"key" must be provided to getConfig()');
   }
-  const isTestEnvironment = getEnvVar('NODE_ENV') === 'test';
 
-  const { warn = !isTestEnvironment, nullishString = false } = options;
+  // override default options with param options
+  const { warn, nullishString, failOnNotFound } = {
+    ...defaultGetConfigOptions,
+    ...options
+  };
 
   const value = getEnvVar(key);
 
-  if (value == null) {
+  // value == null when the key is not present in the env file
+  // value === '' when the key is present but is empty (eg. TEST_CONFIG_VALUE=)
+  if (value == null || value === '') {
+    const notFoundMessage = `getConfig("${key}") returned null or undefined`;
+
+    // error, warn or continue if no value found:
+    if (failOnNotFound) {
+      throw new Error(notFoundMessage);
+    }
     if (warn) {
-      console.warn(`getConfig("${key}") returned null or undefined`);
+      console.warn(notFoundMessage);
     }
     return nullishString ? '' : undefined;
   }