Move credentialToStr and add tests

src/start-proxy.ts

@@ -277,3 +277,14 @@ export async function getDownloadUrl(
     version: UPDATEJOB_PROXY_VERSION,
   };
 }
+
+/**
+ * Pretty-prints a `Credential` value to a string, but hides the actual password or token values.
+ *
+ * @param c The credential to convert to a string.
+ */
+export function credentialToStr(c: Credential): string {
+  return `Type: ${c.type}; Host: ${c.host}; Url: ${c.url} Username: ${
+    c.username
+  }; Password: ${c.password !== undefined}; Token: ${c.token !== undefined}`;
+}