fix(app): ensure already uppercased names stay the same

Author: marcj

packages/app/src/app.ts

@@ -41,11 +41,17 @@ type EnvNamingStrategy =
     | ((name: string) => string | 'same' | 'upper' | 'lower' | undefined);
 
 function camelToUpperCase(str: string) {
-    return str.replace(/[A-Z]+/g, (letter: string) => `_${letter.toUpperCase()}`).toUpperCase();
+    if (/^[A-Z0-9_]+$/.test(str)) return str; // already upper snake case
+    return str
+        .replace(/([a-z0-9])([A-Z])/g, '$1_$2') // insert underscore between lower/number and upper
+        .toUpperCase();
 }
 
 function camelToLowerCase(str: string) {
-    return str.replace(/[A-Z]+/g, (letter: string) => `_${letter.toLowerCase()}`).toLowerCase();
+    if (/^[a-z0-9_]+$/.test(str)) return str; // already lower snake case
+    return str
+        .replace(/([a-z0-9])([A-Z])/g, '$1_$2') // insert underscore
+        .toLowerCase();
 }
 
 function convertNameStrategy(namingStrategy: EnvNamingStrategy, name: string): string {

packages/app/tests/application.spec.ts

@@ -53,6 +53,24 @@ test('loadConfigFromEnvVariables', async () => {
     expect(baseService.db).toBe('changed2');
 });
 
+test('loadConfigFromEnvVariables upper same', async () => {
+    process.env.CC_PREVIEW_INTERNAL_KEY = 'abced';
+    class Config {
+        PREVIEW_INTERNAL_KEY: string = 'default';
+    }
+
+    class Service {
+        constructor(public key: Config['PREVIEW_INTERNAL_KEY']) {
+        }
+    }
+
+    const app = new App({ config: Config, providers: [Service] });
+    app.loadConfigFromEnv({ prefix: 'CC_', namingStrategy: 'upper' });
+
+    const service = app.get(Service);
+    expect(service.key).toBe('abced');
+});
+
 test('loadConfigFromEnvFile', async () => {
     const app = new App({ config: Config, providers: [Service], imports: [new BaseModule] });
     app.loadConfigFromEnv({ envFilePath: dirname + '/test.env' });