Add tests for zstd content-encoding (web-platform-tests#44393)

* add zstd tests and separate into folders

* add bad input tests and make window size test tentative

* add https to bad input test

fetch/content-encoding/zstd/bad-zstd-body.https.any.js

@@ -0,0 +1,22 @@
+// META: global=window,worker
+
+promise_test((test) => {
+    return fetch("resources/bad-zstd-body.py").then(res => {
+      assert_equals(res.status, 200);
+    });
+}, "Fetching a resource with bad zstd content should still resolve");
+
+[
+  "arrayBuffer",
+  "blob",
+  "formData",
+  "json",
+  "text"
+].forEach(method => {
+  promise_test(t => {
+    return fetch("resources/bad-zstd-body.py").then(res => {
+      assert_equals(res.status, 200);
+      return promise_rejects_js(t, TypeError, res[method]());
+    });
+  }, "Consuming the body of a resource with bad zstd content with " + method + "() should reject");
+});

fetch/content-encoding/zstd/big-window-zstd-body.tentative.https.any.js

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+// META: global=window,worker
+// See https://github.com/facebook/zstd/issues/2713 for discussion about
+// standardizing window size limits.
+
+promise_test(async t => {
+  const response = await fetch('resources/big.window.zst');
+  assert_true(response.ok);
+  await promise_rejects_js(t, TypeError, response.text());
+}, 'Consuming the body of a resource with too large of a zstd window size should reject');

fetch/content-encoding/zstd/big-zstd-body.https.any.js

@@ -0,0 +1,55 @@
+// META: global=window,worker
+
+const EXPECTED_SIZE = 27000000;
+const EXPECTED_SHA256 = [
+    74,  100, 37, 243, 147, 61,  116, 60,  241, 221, 126,
+    18,  24,  71, 204, 28,  50,  62,  201, 130, 152, 225,
+    217, 183, 10, 201, 143, 214, 102, 155, 212, 248,
+  ];
+
+promise_test(async () => {
+  const response = await fetch('resources/big.text.zst');
+  assert_true(response.ok);
+  const arrayBuffer = await response.arrayBuffer();
+  assert_equals(arrayBuffer.byteLength, EXPECTED_SIZE,
+               'uncompressed size should match');
+  const sha256 = await crypto.subtle.digest('SHA-256', arrayBuffer);
+  assert_array_equals(new Uint8Array(sha256), EXPECTED_SHA256,
+                      'digest should match');
+}, 'large zstd data should be decompressed successfully');
+
+promise_test(async () => {
+  const response = await fetch('resources/big.text.zst');
+  assert_true(response.ok);
+  const reader = response.body.getReader({mode: 'byob'});
+  let offset = 0;
+  // Pre-allocate space for the output. The response body will be read
+  // chunk-by-chunk into this array.
+  let ab = new ArrayBuffer(EXPECTED_SIZE);
+  while (offset < EXPECTED_SIZE) {
+    // To stress the data pipe, we want to use a different size read each
+    // time. Unfortunately, JavaScript doesn't have a seeded random number
+    // generator, so this creates the possibility of making this test flaky if
+    // it doesn't work for some edge cases.
+    let size = Math.floor(Math.random() * 65535 + 1);
+    if (size + offset > EXPECTED_SIZE) {
+      size = EXPECTED_SIZE - offset;
+    }
+    const u8 = new Uint8Array(ab, offset, size);
+    const { value, done } = await reader.read(u8);
+    ab = value.buffer;
+    // Check that we got our original array back.
+    assert_equals(ab.byteLength, EXPECTED_SIZE,
+                  'backing array should be the same size');
+    assert_equals(offset, value.byteOffset, 'offset should match');
+    assert_less_than_equal(value.byteLength, size,
+                           'we should not have got more than we asked for');
+    offset = value.byteOffset + value.byteLength;
+    if (done) break;
+  }
+  assert_equals(offset, EXPECTED_SIZE,
+                'we should have read the whole thing');
+  const sha256 = await crypto.subtle.digest('SHA-256', new Uint8Array(ab));
+  assert_array_equals(new Uint8Array(sha256), EXPECTED_SHA256,
+                      'digest should match');
+}, 'large zstd data should be decompressed successfully with byte stream');

fetch/content-encoding/zstd/resources/bad-zstd-body.py

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+def main(request, response):
+    headers = [(b"Content-Encoding", b"zstd")]
+    return headers, b"not actually zstd"

fetch/content-encoding/zstd/resources/big.text.zst.headers

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+Content-type: text/plain
+Content-Encoding: zstd
+Cache-Control: no-store

fetch/content-encoding/zstd/resources/big.window.zst.headers

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+Content-type: text/plain
+Content-Encoding: zstd

fetch/content-encoding/zstd/resources/foo.octetstream.zst.headers

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+Content-type: application/octet-stream
+Content-Encoding: zstd

fetch/content-encoding/zstd/resources/foo.text.zst.headers

@@ -0,0 +1,2 @@
+Content-type: text/plain
+Content-Encoding: zstd

fetch/content-encoding/zstd/zstd-body.https.any.js

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+// META: global=window,worker
+
+const expectedDecompressedSize = 10500;
+[
+    "text",
+    "octetstream"
+].forEach(contentType => {
+    promise_test(async t => {
+        let response = await fetch(`resources/foo.${contentType}.zst`);
+        assert_true(response.ok);
+        let arrayBuffer = await response.arrayBuffer()
+        let u8 = new Uint8Array(arrayBuffer);
+        assert_equals(u8.length, expectedDecompressedSize);
+    }, `fetched zstd data with content type ${contentType} should be decompressed.`);
+});