refactor: centralize safe decode helpers

tests/safe-decode.test.mjs

@@ -0,0 +1,70 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import {
+  safeDecodeURIComponent,
+  safeDecodeURIComponentLoose,
+} from "../js/utils/safeDecode.js";
+
+import { safeDecodeMagnet } from "../js/magnetUtils.js";
+
+test("safeDecodeURIComponent returns original value on malformed sequences", () => {
+  const malformed = "%E0%A4%A";
+  assert.equal(
+    safeDecodeURIComponent(malformed),
+    malformed,
+    "Malformed sequences should return the original input"
+  );
+});
+
+test("safeDecode helpers handle double-encoded values when applied repeatedly", () => {
+  const raw = "magnet:?xt=urn:btih:abcdef";
+  const doubleEncoded = encodeURIComponent(encodeURIComponent(raw));
+
+  const firstPass = safeDecodeURIComponent(doubleEncoded);
+  assert.equal(
+    firstPass,
+    encodeURIComponent(raw),
+    "First pass should peel one encoding layer"
+  );
+
+  const secondPass = safeDecodeURIComponent(firstPass);
+  assert.equal(
+    secondPass,
+    raw,
+    "Second pass should reveal the original string"
+  );
+
+  assert.equal(
+    safeDecodeMagnet(doubleEncoded),
+    raw,
+    "safeDecodeMagnet should continue to handle double-encoded magnets"
+  );
+});
+
+test("safeDecodeURIComponentLoose trims inputs by default", () => {
+  const padded = "   magnet:?dn=Example";
+  assert.equal(
+    safeDecodeURIComponentLoose(padded),
+    "magnet:?dn=Example",
+    "Loose decoder should trim whitespace when decoding"
+  );
+});
+
+test("safeDecodeURIComponentLoose preserves whitespace when trim is false", () => {
+  const padded = "   magnet:?dn=Example";
+  assert.equal(
+    safeDecodeURIComponentLoose(padded, { trim: false }),
+    padded,
+    "Loose decoder should return the original string when trim is disabled and decoding is unnecessary"
+  );
+});
+
+test("safeDecodeURIComponent handles empty strings consistently", () => {
+  assert.equal(safeDecodeURIComponent(""), "", "Empty input should stay empty");
+  assert.equal(
+    safeDecodeURIComponentLoose(""),
+    "",
+    "Loose decoder should return empty for empty input"
+  );
+});