test: cover SDK UTF-8 base64 helpers

sdk/typescript/src/__tests__/base64.test.ts

@@ -0,0 +1,70 @@
+import { describe, expect, it } from "bun:test";
+import { decodeBase64ToUtf8, encodeUtf8ToBase64 } from "../base64";
+
+const originalAtob = Object.getOwnPropertyDescriptor(globalThis, "atob");
+const originalBtoa = Object.getOwnPropertyDescriptor(globalThis, "btoa");
+
+function withoutGlobal(name: "atob" | "btoa", callback: () => void): void {
+  const original = Object.getOwnPropertyDescriptor(globalThis, name);
+  try {
+    Object.defineProperty(globalThis, name, {
+      configurable: true,
+      writable: true,
+      value: undefined,
+    });
+    callback();
+  } finally {
+    if (original) {
+      Object.defineProperty(globalThis, name, original);
+    } else {
+      delete (globalThis as Record<string, unknown>)[name];
+    }
+  }
+}
+
+describe("UTF-8 base64 helpers", () => {
+  it.each([
+    ["ASCII", "Hello, world!"],
+    ["accented text", "Café déjà vu"],
+    ["non-Latin text", "नमस्ते мир"],
+    ["emoji", "Paygate 🚀✅"],
+  ])("round-trips %s", (_label, value) => {
+    expect(decodeBase64ToUtf8(encodeUtf8ToBase64(value))).toBe(value);
+  });
+
+  it("encodes empty text as an empty string", () => {
+    expect(encodeUtf8ToBase64("")).toBe("");
+  });
+
+  it("matches a known base64 fixture", () => {
+    expect(encodeUtf8ToBase64("Hello, world!")).toBe("SGVsbG8sIHdvcmxkIQ==");
+    expect(decodeBase64ToUtf8("SGVsbG8sIHdvcmxkIQ==")).toBe("Hello, world!");
+  });
+
+  it.each(["", " SGVsbG8=", "SGVsbG8= ", "SGVsbG8", "SGVsbG8$", "===="]) (
+    "rejects invalid base64 input %j",
+    (value) => {
+      expect(() => decodeBase64ToUtf8(value)).toThrow("invalid base64");
+    },
+  );
+
+  it("reports a missing atob capability and restores it after the assertion", () => {
+    withoutGlobal("atob", () => {
+      expect(() => decodeBase64ToUtf8("SGVsbG8=")).toThrow(
+        "base64 decoding is unavailable in this runtime",
+      );
+    });
+
+    expect(Object.getOwnPropertyDescriptor(globalThis, "atob")).toEqual(originalAtob);
+  });
+
+  it("reports a missing btoa capability and restores it after the assertion", () => {
+    withoutGlobal("btoa", () => {
+      expect(() => encodeUtf8ToBase64("hello")).toThrow(
+        "base64 encoding is unavailable in this runtime",
+      );
+    });
+
+    expect(Object.getOwnPropertyDescriptor(globalThis, "btoa")).toEqual(originalBtoa);
+  });
+});