fix(auth-oauth1): use the signing key as the PLAINTEXT signature (#605)

plugins/auth-oauth1/tests/plaintext.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, test } from "vite-plus/test";
+import { plugin } from "../src";
+
+function sign(values: Record<string, string>): string {
+  const result = plugin.authentication!.onApply!(
+    {} as never,
+    {
+      values,
+      method: "GET",
+      url: "https://api.example.com/resource",
+    } as never,
+  ) as { setHeaders: { name: string; value: string }[] };
+  const header = result.setHeaders[0]!.value;
+  const match = header.match(/oauth_signature="([^"]*)"/);
+  return decodeURIComponent(match![1]!);
+}
+
+describe("PLAINTEXT signature", () => {
+  const base = {
+    signatureMethod: "PLAINTEXT",
+    consumerKey: "ck",
+    consumerSecret: "cs",
+    nonce: "abc123",
+    timestamp: "1700000000",
+  };
+
+  // RFC 5849 3.4.4: the PLAINTEXT signature is the signing key itself --
+  // encoded(consumer secret) "&" encoded(token secret) -- not the base string.
+  test("is the signing key, not the signature base string", () => {
+    expect(sign({ ...base, tokenKey: "tk", tokenSecret: "ts" })).toBe("cs&ts");
+  });
+
+  test("keeps the trailing separator when there is no token secret", () => {
+    expect(sign(base)).toBe("cs&");
+  });
+
+  test("percent-encodes reserved characters in the secrets", () => {
+    expect(sign({ ...base, consumerSecret: "c s", tokenKey: "tk", tokenSecret: "t&s" })).toBe(
+      "c%20s&t%26s",
+    );
+  });
+});