fix(caniuse): handle wf- prefixed web-features IDs

routes/caniuse/feature.ts

@@ -1,5 +1,4 @@
 import { Request, Response } from "express";
-import { seconds } from "../../utils/misc.js";
 import { BROWSERS, DEFAULT_BROWSERS } from "./lib/constants.js";
 import { Data, getData } from "./lib/index.js";
 
@@ -11,25 +10,23 @@ export default async function route(req: IRequest, res: Response) {
   const { feature } = req.params;
   const browsers = normalizeBrowsers(req.query.browsers);
 
-
   try {
     const data = await getData(feature);
     if (data === null) {
-      res.sendStatus(404);
+      const hint = feature.startsWith("wf-") && feature.length > 3
+        ? ` The "wf-" prefix indicates a web-features ID. No matching caniuse data was found for "${feature}" or "${feature.slice(3)}".`
+        : "";
+      res.status(404).json({ error: `Feature "${feature}" not found.${hint}` });
       return;
     }
     const result = [];
     for (const browser of browsers) {
-      result.push({ browser, ...getBrowserData(data?.all[browser]) });
+      result.push({ browser, ...getBrowserData(data.all[browser]) });
     }
     res.json({ result });
   } catch (error) {
     const message = error instanceof Error ? error.message : String(error);
-    const errorCode = message === "INTERNAL_ERROR" ? 500 : 404;
-    console.error("caniuse feature route error", error);
-    res.status(errorCode);
-    res.setHeader("Content-Type", "text/plain");
-    res.send(errorCode === 500 ? "Internal Server Error" : "Not Found");
+    res.status(500).json({ error: message });
   }
 }
 

routes/caniuse/index.ts

@@ -49,3 +49,4 @@ export async function route(req: IRequest, res: Response) {
   res.set("Cache-Control", `max-age=${seconds("24h")}`);
   res.send(body);
 }
+

routes/caniuse/lib/index.ts

@@ -15,6 +15,7 @@ import {
 export { Data };
 
 const DATA_DIR = env("DATA_DIR");
+const CANIUSE_DIR = path.join(DATA_DIR, "caniuse");
 
 interface Options {
   feature: string;
@@ -106,11 +107,28 @@ function sanitizeBrowsersList(browsers?: string | string[]) {
 }
 
 export async function getData(feature: string) {
+  if (typeof feature !== "string" || !feature) return null;
+  if (!/^[a-z0-9][a-z0-9._-]*$/i.test(feature)) return null;
+  // Try the feature as-is first, then fall back to stripping the "wf-" prefix.
+  // E.g., "wf-css-grid" falls back to looking up "css-grid" in caniuse data.
+  const data = await readFeatureFile(feature);
+  if (data) return data;
+  if (feature.startsWith("wf-") && feature.length > 3) {
+    const fallbackData = await readFeatureFile(feature.slice(3));
+    if (fallbackData) {
+      cache.set(feature, fallbackData);
+    }
+    return fallbackData;
+  }
+  return null;
+}
+
+async function readFeatureFile(feature: string) {
   if (cache.has(feature)) {
     return cache.get(feature) as Data;
   }
   const file = path.format({
-    dir: path.join(DATA_DIR, "caniuse"),
+    dir: CANIUSE_DIR,
     name: `${feature}.json`,
   });
 
@@ -120,8 +138,11 @@ export async function getData(feature: string) {
     cache.set(feature, data);
     return data;
   } catch (error) {
-    console.error(error);
-    return null;
+    const code = (error as NodeJS.ErrnoException).code;
+    if (code === "ENOENT") {
+      return null;
+    }
+    throw error;
   }
 }
 

tests/routes/caniuse/feature.test.js

@@ -0,0 +1,144 @@
+import os from "node:os";
+import path from "node:path";
+import { promises as fs } from "node:fs";
+
+import route from "../../../build/routes/caniuse/feature.js";
+import { cache } from "../../../build/routes/caniuse/lib/index.js";
+
+const CANIUSE_DIR = path.join(os.tmpdir(), "caniuse");
+
+const FIXTURE = {
+  all: {
+    chrome: [["100", ["y"]]],
+    firefox: [["99", ["n"]]],
+    edge: [["100", ["y"]]],
+    safari: [["16", ["y"]]],
+    and_chr: [["100", ["y"]]],
+    and_ff: [["99", ["n"]]],
+    ios_saf: [["16", ["y"]]],
+    samsung: [["19", ["y"]]],
+  },
+  summary: { chrome: [["100", ["y"]]] },
+};
+
+/** Builds a lightweight mock Express Response. */
+function mockRes() {
+  const res = {
+    statusCode: 200,
+    body: null,
+    status(code) {
+      this.statusCode = code;
+      return this;
+    },
+    json(body) {
+      this.body = body;
+      return this;
+    },
+    send(body) {
+      this.body = body;
+      return this;
+    },
+    type(_t) {
+      return this;
+    },
+  };
+  return res;
+}
+
+/** Builds a minimal mock Express Request for the `/:feature` route. */
+function mockReq(feature, query = {}) {
+  return { params: { feature }, query };
+}
+
+async function writeFixture(name, data = FIXTURE) {
+  await fs.mkdir(CANIUSE_DIR, { recursive: true });
+  await fs.writeFile(
+    path.join(CANIUSE_DIR, `${name}.json`),
+    JSON.stringify(data),
+    "utf8",
+  );
+}
+
+async function removeFixture(name) {
+  try {
+    await fs.unlink(path.join(CANIUSE_DIR, `${name}.json`));
+  } catch {
+    // ignore
+  }
+}
+
+describe("caniuse - feature route", () => {
+  beforeEach(() => cache.clear());
+
+  describe("404 responses", () => {
+    it("returns JSON 404 for a missing feature", async () => {
+      const res = mockRes();
+      await route(mockReq("nonexistent-xyz"), res);
+      expect(res.statusCode).toBe(404);
+      expect(res.body).toEqual(jasmine.objectContaining({ error: jasmine.any(String) }));
+      expect(res.body.error).toContain("nonexistent-xyz");
+    });
+
+    it("returns JSON 404 with a wf- hint for a missing wf- feature", async () => {
+      const res = mockRes();
+      await route(mockReq("wf-no-such-feature-xyz"), res);
+      expect(res.statusCode).toBe(404);
+      expect(res.body.error).toContain("wf-");
+      expect(res.body.error).toContain("web-features");
+    });
+
+    it("returns JSON 404 without wf- hint for the edge case 'wf-'", async () => {
+      const res = mockRes();
+      await route(mockReq("wf-"), res);
+      expect(res.statusCode).toBe(404);
+      expect(res.body.error).not.toContain("web-features");
+    });
+  });
+
+  describe("successful responses", () => {
+    it("returns 200 JSON with browser data for a known feature", async () => {
+      await writeFixture("css-grid");
+      try {
+        const res = mockRes();
+        await route(mockReq("css-grid"), res);
+        expect(res.statusCode).toBe(200);
+        expect(res.body).toEqual(jasmine.objectContaining({ result: jasmine.any(Array) }));
+      } finally {
+        await removeFixture("css-grid");
+      }
+    });
+
+    it("resolves wf- prefixed feature to its caniuse equivalent", async () => {
+      await writeFixture("css-grid");
+      try {
+        const res = mockRes();
+        await route(mockReq("wf-css-grid"), res);
+        expect(res.statusCode).toBe(200);
+        expect(res.body.result).toBeDefined();
+      } finally {
+        await removeFixture("css-grid");
+      }
+    });
+  });
+
+  describe("500 responses", () => {
+    it("returns JSON 500 when the feature file is malformed JSON", async () => {
+      await fs.mkdir(CANIUSE_DIR, { recursive: true });
+      await fs.writeFile(
+        path.join(CANIUSE_DIR, "broken-feature.json"),
+        "not valid json",
+        "utf8",
+      );
+      try {
+        const res = mockRes();
+        await route(mockReq("broken-feature"), res);
+        expect(res.statusCode).toBe(500);
+        expect(res.body).toEqual(jasmine.objectContaining({ error: jasmine.any(String) }));
+      } finally {
+        try {
+          await fs.unlink(path.join(CANIUSE_DIR, "broken-feature.json"));
+        } catch { /* ignore */ }
+      }
+    });
+  });
+});

tests/routes/caniuse/lib/index.test.js

@@ -0,0 +1,102 @@
+import os from "node:os";
+import path from "node:path";
+import { promises as fs } from "node:fs";
+
+import {
+  getData,
+  cache,
+} from "../../../../build/routes/caniuse/lib/index.js";
+
+const CANIUSE_DIR = path.join(os.tmpdir(), "caniuse");
+
+/** Minimal valid ScraperOutput fixture */
+const FIXTURE = {
+  all: { chrome: [["100", ["y"]]], firefox: [["99", ["n"]]] },
+  summary: { chrome: [["100", ["y"]]] },
+};
+
+async function writeFixture(name, data = FIXTURE) {
+  await fs.mkdir(CANIUSE_DIR, { recursive: true });
+  await fs.writeFile(
+    path.join(CANIUSE_DIR, `${name}.json`),
+    JSON.stringify(data),
+    "utf8",
+  );
+}
+
+async function removeFixture(name) {
+  try {
+    await fs.unlink(path.join(CANIUSE_DIR, `${name}.json`));
+  } catch {
+    // ignore – file may not exist
+  }
+}
+
+describe("caniuse - getData", () => {
+  beforeEach(() => cache.clear());
+
+  it("returns null for empty feature string", async () => {
+    expect(await getData("")).toBeNull();
+  });
+
+  it("returns null for invalid characters (path traversal attempt)", async () => {
+    expect(await getData("../etc/passwd")).toBeNull();
+    expect(await getData("foo/bar")).toBeNull();
+    expect(await getData("feature name")).toBeNull();
+  });
+
+  it("returns null for non-existent feature", async () => {
+    expect(await getData("nonexistent-feature-xyz")).toBeNull();
+  });
+
+  it("returns data for a known feature", async () => {
+    await writeFixture("css-grid");
+    try {
+      const data = await getData("css-grid");
+      expect(data).toEqual(FIXTURE);
+    } finally {
+      await removeFixture("css-grid");
+    }
+  });
+
+  it("returns null for wf- edge case (exactly 'wf-')", async () => {
+    expect(await getData("wf-")).toBeNull();
+  });
+
+  it("returns null for wf- feature where stripped name also has no data", async () => {
+    expect(await getData("wf-no-such-feature-xyz")).toBeNull();
+  });
+
+  it("falls back from wf- prefixed key to the stripped feature name", async () => {
+    await writeFixture("css-grid");
+    try {
+      const data = await getData("wf-css-grid");
+      expect(data).toEqual(FIXTURE);
+    } finally {
+      await removeFixture("css-grid");
+    }
+  });
+
+  it("caches the result under the original wf- key after a successful fallback", async () => {
+    await writeFixture("css-grid");
+    try {
+      expect(cache.has("wf-css-grid")).toBeFalse();
+      await getData("wf-css-grid");
+      expect(cache.has("wf-css-grid")).toBeTrue();
+    } finally {
+      await removeFixture("css-grid");
+    }
+  });
+
+  it("serves subsequent wf- requests from cache without extra disk I/O", async () => {
+    await writeFixture("css-grid");
+    try {
+      await getData("wf-css-grid"); // warm up cache
+      await removeFixture("css-grid"); // remove file; only cache should serve it now
+      const data = await getData("wf-css-grid");
+      expect(data).toEqual(FIXTURE);
+    } finally {
+      await removeFixture("css-grid");
+    }
+  });
+});