If baseUriPath is set format it, but if it's not, don't override default with empty string (#2118)

From Thomas and mine testing. BaseUriPath can't be set as an environment
variable because we override it when trying to format the URI from the
server config. This PR makes sure we only format if the custom server
options actually have baseUriPath set.

Co-authored-by: Thomas Heartman <thomas@getunleash.ai>

src/lib/create-config.test.ts

@@ -428,3 +428,37 @@ test('Environment variables for frontend CORS origins takes priority over option
     delete process.env.UNLEASH_FRONTEND_API_ORIGINS;
     expect(create()).toEqual(['*']);
 });
+
+test('baseUriPath defaults to the empty string', async () => {
+    let config = createConfig({});
+    expect(config.server.baseUriPath).toBe('');
+});
+test('BASE_URI_PATH defined in env is passed through', async () => {
+    process.env.BASE_URI_PATH = '/demo';
+    let config = createConfig({});
+    expect(config.server.baseUriPath).toBe('/demo');
+    delete process.env.BASE_URI_PATH;
+});
+
+test('environment variable takes precedence over configured variable', async () => {
+    process.env.BASE_URI_PATH = '/demo';
+    let config = createConfig({
+        server: {
+            baseUriPath: '/other',
+        },
+    });
+    expect(config.server.baseUriPath).toBe('/demo');
+    delete process.env.BASE_URI_PATH;
+});
+
+test.each(['demo', '/demo', '/demo/'])(
+    'Trailing and leading slashes gets normalized for base path %s',
+    async (path) => {
+        let config = createConfig({
+            server: {
+                baseUriPath: path,
+            },
+        });
+        expect(config.server.baseUriPath).toBe('/demo');
+    },
+);

src/lib/create-config.ts

@@ -231,12 +231,18 @@ const removeUndefinedKeys = (o: object): object =>
 const formatServerOptions = (
     serverOptions?: Partial<IServerOption>,
 ): Partial<IServerOption> | undefined => {
-    if (!serverOptions) return;
+    if (!serverOptions) {
+        return {
+            baseUriPath: formatBaseUri(process.env.BASE_URI_PATH),
+        };
+    }
 
     /* eslint-disable-next-line */
     return {
         ...serverOptions,
-        baseUriPath: formatBaseUri(serverOptions.baseUriPath),
+        baseUriPath: formatBaseUri(
+            process.env.BASE_URI_PATH || serverOptions.baseUriPath,
+        ),
     };
 };