Merge pull request #3 from zazuko/remote-improvements

fix: handle fetch fails

.changeset/selfish-pens-mix.md

@@ -0,0 +1,5 @@
+---
+"rdf-transform-graph-imports": patch
+---
+
+Failures to fetch remote import would break the stream

index.ts

@@ -31,8 +31,8 @@ function transform(env: Environment, { basePath }: Options = {}) {
         })
 
       for (const importTarget of imports) {
-        const importStream = fetchImport(env, importTarget)
-          .pipe(transform(env, { basePath: importTarget }))
+        const fetchStream = await fetchImport(env, importTarget)
+        const importStream = fetchStream.pipe(transform(env, { basePath: importTarget }))
 
         for await (const importedQuad of importStream) {
           this.push(importedQuad)

lib/fetchImport.ts

@@ -1,23 +1,15 @@
-import { Readable, PassThrough } from 'readable-stream'
+import { Readable } from 'readable-stream'
 import Environment from './env.js'
 
-export default function (env: Environment, importTarget: string | URL) {
+export default async function (env: Environment, importTarget: string | URL) {
   if (typeof importTarget === 'string') {
     return env.fromFile(importTarget)
   }
 
-  const remoteStream = new PassThrough({ objectMode: true })
-
-  env.fetch(importTarget.toString())
-    .then(response => {
-      return response.quadStream() as unknown as Promise<Readable>
-    })
-    .then(quadStream => {
-      quadStream.pipe(remoteStream)
-    })
-    .catch(error => {
-      remoteStream.emit('error', error)
-    })
+  const response = await env.fetch(importTarget.toString())
+  if (!response.ok) {
+    throw new Error(`Failed to fetch: ${response.statusText}`)
+  }
 
-  return remoteStream
+  return response.quadStream() as unknown as Promise<Readable>
 }

package.json

@@ -48,6 +48,7 @@
     "@tpluscode/eslint-config": "^0.4.4",
     "@types/absolute-url": "^2.0.0",
     "@types/chai": "^4.3.9",
+    "@types/chai-as-promised": "^7.1.8",
     "@types/express": "^4.17.20",
     "@types/is-uri": "^1.0.2",
     "@types/mocha": "^10.0.3",
@@ -60,6 +61,7 @@
     "absolute-url": "^2.0.0",
     "c8": "^8.0.1",
     "chai": "^4.3.10",
+    "chai-as-promised": "^7.1.1",
     "eslint-import-resolver-typescript": "^3.6.1",
     "express": "^4.18.2",
     "husky": "^8.0.3",
@@ -77,6 +79,9 @@
   },
   "mocha": {
     "extension": "ts",
-    "loader": "ts-node/esm"
+    "loader": "ts-node/esm",
+    "require": [
+      "test/mocha-setup.cjs"
+    ]
   }
 }

test/index.test.ts

@@ -59,6 +59,16 @@ describe('rdf-merge-stream', () => {
     // then
     expect(await turtle(merged)).toMatchSnapshot()
   })
+
+  it('fails when remote resource is not found', async () => {
+    // given
+    const response = await rdf.fetch('http://localhost:6666/invalid-import')
+    const root = await response.quadStream() as unknown as Readable
+
+    // then
+    await expect(rdf.dataset().import(root.pipe(transform(rdf))))
+      .to.be.eventually.rejectedWith('Failed to fetch: Not Found')
+  })
 })
 
 async function turtle(merged: Dataset) {

test/mocha-setup.cjs

@@ -0,0 +1,4 @@
+const chai = require('chai')
+const chaiAsPromised = require('chai-as-promised')
+
+chai.use(chaiAsPromised);

test/server/index.ts

@@ -1,5 +1,6 @@
 import * as url from 'url'
 import * as path from 'path'
+import * as fs from 'fs'
 import express from 'express'
 import * as absoluteUrl from 'absolute-url'
 import rdfHandler from '@rdfjs/express-handler'
@@ -14,7 +15,12 @@ export function start() {
     .get('/*', (req, res) => {
       res.setHeader('Content-Type', 'text/turtle')
 
-      const quads = env.fromFile(path.join(__dirname, `${req.path}.ttl`), {
+      const ttlPath = path.join(__dirname, `${req.path}.ttl`)
+      if (!fs.existsSync(ttlPath)) {
+        return res.sendStatus(404)
+      }
+
+      const quads = env.fromFile(ttlPath, {
         baseUri: req.absoluteUrl(),
       })
 

test/server/resources/invalid-import.ttl

@@ -0,0 +1,7 @@
+PREFIX code: <https://code.described.at/>
+PREFIX schema: <http://schema.org/>
+PREFIX sh: <http://www.w3.org/ns/shacl#>
+
+[
+  code:imports <foobar> ;
+] .