diff --git a/crates/cli/tests/reference.rs b/crates/cli/tests/reference.rs
index 6a4c57956df..df9c7d27399 100644
--- a/crates/cli/tests/reference.rs
+++ b/crates/cli/tests/reference.rs
@@ -8,6 +8,27 @@
 //! `*.js` files and `*.wat` files with the expected output of the `*.rs`
 //! compilation. Use `BLESS=1` in the environment to automatically update all
 //! tests.
+//!
+//! ## Dependencies
+//!
+//! By default, tests only have access to the `wasm-bindgen` and
+//! `wasm-bindgen-futures` crates. Additional crates can be used by declaring
+//! them as dependencies using a comment at the top of the test file.
+//! For example:
+//!
+//! ```rust
+//! // DEPENDENCY: web-sys = { path = '{root}/crates/web-sys', features = ['console', 'Url', 'MediaSourceReadyState'] }
+//! ```
+//!
+//! This will add the `web-sys` crate as a dependency to the test, allowing the
+//! test to use the `console`, `Url`, and `MediaSourceReadyState` features, as
+//! well as the `web-sys` crate itself.
+//!
+//! Note that the `{root}` placeholder will be replaced with the path to the
+//! root of the `wasm-bindgen` repository.
+//!
+//! Multiple dependencies can be declared in a single test file using multiple
+//! `DEPENDENCY:` comments.
 
 use anyhow::{bail, Result};
 use assert_cmd::prelude::*;
@@ -55,6 +76,15 @@ fn main() -> Result<()> {
 fn runtest(test: &Path) -> Result<()> {
     let contents = fs::read_to_string(test)?;
     let td = tempfile::TempDir::new()?;
+    let root = repo_root();
+    let root = root.display();
+
+    // parse additional dependency declarations
+    let dependencies = contents
+        .lines()
+        .filter_map(|l| l.strip_prefix("// DEPENDENCY: "))
+        .map(|l| "\n            ".to_string() + &l.trim().replace("{root}", &root.to_string()))
+        .fold(String::new(), |a, b| a + &b);
 
     let manifest = format!(
         "
@@ -65,16 +95,15 @@ fn runtest(test: &Path) -> Result<()> {
             edition = '2021'
 
             [dependencies]
-            wasm-bindgen = {{ path = '{}' }}
-            wasm-bindgen-futures = {{ path = '{}/crates/futures' }}
+            wasm-bindgen = {{ path = '{root}' }}
+            wasm-bindgen-futures = {{ path = '{root}/crates/futures' }}
+            {dependencies}
 
             [lib]
             crate-type = ['cdylib']
-            path = '{}'
+            path = '{test}'
         ",
-        repo_root().display(),
-        repo_root().display(),
-        test.display(),
+        test = test.display(),
     );
 
     fs::write(td.path().join("Cargo.toml"), manifest)?;
diff --git a/crates/cli/tests/reference/web-sys.d.ts b/crates/cli/tests/reference/web-sys.d.ts
new file mode 100644
index 00000000000..317ce71a92b
--- /dev/null
+++ b/crates/cli/tests/reference/web-sys.d.ts
@@ -0,0 +1,10 @@
+/* tslint:disable */
+/* eslint-disable */
+/**
+ * @returns {URL}
+ */
+export function get_url(): URL;
+/**
+ * @returns {any}
+ */
+export function get_media_source(): any;
diff --git a/crates/cli/tests/reference/web-sys.js b/crates/cli/tests/reference/web-sys.js
new file mode 100644
index 00000000000..58229dc66a1
--- /dev/null
+++ b/crates/cli/tests/reference/web-sys.js
@@ -0,0 +1,235 @@
+let wasm;
+export function __wbg_set_wasm(val) {
+    wasm = val;
+}
+
+
+const heap = new Array(128).fill(undefined);
+
+heap.push(undefined, null, true, false);
+
+function getObject(idx) { return heap[idx]; }
+
+function debugString(val) {
+    // primitive types
+    const type = typeof val;
+    if (type == 'number' || type == 'boolean' || val == null) {
+        return  `${val}`;
+    }
+    if (type == 'string') {
+        return `"${val}"`;
+    }
+    if (type == 'symbol') {
+        const description = val.description;
+        if (description == null) {
+            return 'Symbol';
+        } else {
+            return `Symbol(${description})`;
+        }
+    }
+    if (type == 'function') {
+        const name = val.name;
+        if (typeof name == 'string' && name.length > 0) {
+            return `Function(${name})`;
+        } else {
+            return 'Function';
+        }
+    }
+    // objects
+    if (Array.isArray(val)) {
+        const length = val.length;
+        let debug = '[';
+        if (length > 0) {
+            debug += debugString(val[0]);
+        }
+        for(let i = 1; i < length; i++) {
+            debug += ', ' + debugString(val[i]);
+        }
+        debug += ']';
+        return debug;
+    }
+    // Test for built-in
+    const builtInMatches = /\[object ([^\]]+)\]/.exec(toString.call(val));
+    let className;
+    if (builtInMatches.length > 1) {
+        className = builtInMatches[1];
+    } else {
+        // Failed to match the standard '[object ClassName]'
+        return toString.call(val);
+    }
+    if (className == 'Object') {
+        // we're a user defined class or Object
+        // JSON.stringify avoids problems with cycles, and is generally much
+        // easier than looping through ownProperties of `val`.
+        try {
+            return 'Object(' + JSON.stringify(val) + ')';
+        } catch (_) {
+            return 'Object';
+        }
+    }
+    // errors
+    if (val instanceof Error) {
+        return `${val.name}: ${val.message}\n${val.stack}`;
+    }
+    // TODO we could test for more things here, like `Set`s and `Map`s.
+    return className;
+}
+
+let WASM_VECTOR_LEN = 0;
+
+let cachedUint8ArrayMemory0 = null;
+
+function getUint8ArrayMemory0() {
+    if (cachedUint8ArrayMemory0 === null || cachedUint8ArrayMemory0.byteLength === 0) {
+        cachedUint8ArrayMemory0 = new Uint8Array(wasm.memory.buffer);
+    }
+    return cachedUint8ArrayMemory0;
+}
+
+const lTextEncoder = typeof TextEncoder === 'undefined' ? (0, module.require)('util').TextEncoder : TextEncoder;
+
+let cachedTextEncoder = new lTextEncoder('utf-8');
+
+const encodeString = (typeof cachedTextEncoder.encodeInto === 'function'
+    ? function (arg, view) {
+    return cachedTextEncoder.encodeInto(arg, view);
+}
+    : function (arg, view) {
+    const buf = cachedTextEncoder.encode(arg);
+    view.set(buf);
+    return {
+        read: arg.length,
+        written: buf.length
+    };
+});
+
+function passStringToWasm0(arg, malloc, realloc) {
+
+    if (realloc === undefined) {
+        const buf = cachedTextEncoder.encode(arg);
+        const ptr = malloc(buf.length, 1) >>> 0;
+        getUint8ArrayMemory0().subarray(ptr, ptr + buf.length).set(buf);
+        WASM_VECTOR_LEN = buf.length;
+        return ptr;
+    }
+
+    let len = arg.length;
+    let ptr = malloc(len, 1) >>> 0;
+
+    const mem = getUint8ArrayMemory0();
+
+    let offset = 0;
+
+    for (; offset < len; offset++) {
+        const code = arg.charCodeAt(offset);
+        if (code > 0x7F) break;
+        mem[ptr + offset] = code;
+    }
+
+    if (offset !== len) {
+        if (offset !== 0) {
+            arg = arg.slice(offset);
+        }
+        ptr = realloc(ptr, len, len = offset + arg.length * 3, 1) >>> 0;
+        const view = getUint8ArrayMemory0().subarray(ptr + offset, ptr + len);
+        const ret = encodeString(arg, view);
+
+        offset += ret.written;
+        ptr = realloc(ptr, len, offset, 1) >>> 0;
+    }
+
+    WASM_VECTOR_LEN = offset;
+    return ptr;
+}
+
+let cachedDataViewMemory0 = null;
+
+function getDataViewMemory0() {
+    if (cachedDataViewMemory0 === null || cachedDataViewMemory0.buffer.detached === true || (cachedDataViewMemory0.buffer.detached === undefined && cachedDataViewMemory0.buffer !== wasm.memory.buffer)) {
+        cachedDataViewMemory0 = new DataView(wasm.memory.buffer);
+    }
+    return cachedDataViewMemory0;
+}
+
+const lTextDecoder = typeof TextDecoder === 'undefined' ? (0, module.require)('util').TextDecoder : TextDecoder;
+
+let cachedTextDecoder = new lTextDecoder('utf-8', { ignoreBOM: true, fatal: true });
+
+cachedTextDecoder.decode();
+
+function getStringFromWasm0(ptr, len) {
+    ptr = ptr >>> 0;
+    return cachedTextDecoder.decode(getUint8ArrayMemory0().subarray(ptr, ptr + len));
+}
+
+let heap_next = heap.length;
+
+function dropObject(idx) {
+    if (idx < 132) return;
+    heap[idx] = heap_next;
+    heap_next = idx;
+}
+
+function takeObject(idx) {
+    const ret = getObject(idx);
+    dropObject(idx);
+    return ret;
+}
+/**
+ * @returns {URL}
+ */
+export function get_url() {
+    const ret = wasm.get_url();
+    return takeObject(ret);
+}
+
+/**
+ * @returns {any}
+ */
+export function get_media_source() {
+    const ret = wasm.get_media_source();
+    return __wbindgen_enum_MediaSourceEnum[ret];
+}
+
+function addHeapObject(obj) {
+    if (heap_next === heap.length) heap.push(heap.length + 1);
+    const idx = heap_next;
+    heap_next = heap[idx];
+
+    heap[idx] = obj;
+    return idx;
+}
+
+function handleError(f, args) {
+    try {
+        return f.apply(this, args);
+    } catch (e) {
+        wasm.__wbindgen_exn_store(addHeapObject(e));
+    }
+}
+
+const __wbindgen_enum_MediaSourceEnum = ["camera", "screen", "application", "window", "browser", "microphone", "audioCapture", "other"];
+
+const __wbindgen_enum_MediaSourceReadyState = ["closed", "open", "ended"];
+
+export function __wbg_new_1cabf49927794f50() { return handleError(function (arg0, arg1) {
+    const ret = new URL(getStringFromWasm0(arg0, arg1));
+    return addHeapObject(ret);
+}, arguments) };
+
+export function __wbindgen_debug_string(arg0, arg1) {
+    const ret = debugString(getObject(arg1));
+    const ptr1 = passStringToWasm0(ret, wasm.__wbindgen_malloc, wasm.__wbindgen_realloc);
+    const len1 = WASM_VECTOR_LEN;
+    getDataViewMemory0().setInt32(arg0 + 4 * 1, len1, true);
+    getDataViewMemory0().setInt32(arg0 + 4 * 0, ptr1, true);
+};
+
+export function __wbindgen_throw(arg0, arg1) {
+    throw new Error(getStringFromWasm0(arg0, arg1));
+};
+
+export function __wbindgen_object_drop_ref(arg0) {
+    takeObject(arg0);
+};
+
diff --git a/crates/cli/tests/reference/web-sys.rs b/crates/cli/tests/reference/web-sys.rs
new file mode 100644
index 00000000000..6ad4315c2ed
--- /dev/null
+++ b/crates/cli/tests/reference/web-sys.rs
@@ -0,0 +1,15 @@
+// DEPENDENCY: web-sys = { path = '{root}/crates/web-sys', features = ['console', 'Url', 'MediaSourceEnum', 'MediaSourceReadyState'] }
+
+use wasm_bindgen::prelude::wasm_bindgen;
+use web_sys::{Url, MediaSourceEnum, MediaSourceReadyState};
+
+#[wasm_bindgen]
+pub fn get_url() -> Url {
+    assert_eq!(MediaSourceReadyState::Closed, MediaSourceReadyState::Closed);
+    Url::new("https://example.com").unwrap()
+}
+
+#[wasm_bindgen]
+pub fn get_media_source() -> MediaSourceEnum {
+    MediaSourceEnum::Camera
+}
diff --git a/crates/cli/tests/reference/web-sys.wat b/crates/cli/tests/reference/web-sys.wat
new file mode 100644
index 00000000000..eefb7ad3e97
--- /dev/null
+++ b/crates/cli/tests/reference/web-sys.wat
@@ -0,0 +1,20 @@
+(module $reference_test.wasm
+  (type (;0;) (func (result i32)))
+  (type (;1;) (func (param i32)))
+  (type (;2;) (func (param i32 i32) (result i32)))
+  (type (;3;) (func (param i32 i32 i32 i32) (result i32)))
+  (func $__wbindgen_realloc (;0;) (type 3) (param i32 i32 i32 i32) (result i32))
+  (func $__wbindgen_malloc (;1;) (type 2) (param i32 i32) (result i32))
+  (func $get_url (;2;) (type 0) (result i32))
+  (func $get_media_source (;3;) (type 0) (result i32))
+  (func $__wbindgen_exn_store (;4;) (type 1) (param i32))
+  (memory (;0;) 17)
+  (export "memory" (memory 0))
+  (export "get_url" (func $get_url))
+  (export "get_media_source" (func $get_media_source))
+  (export "__wbindgen_malloc" (func $__wbindgen_malloc))
+  (export "__wbindgen_realloc" (func $__wbindgen_realloc))
+  (export "__wbindgen_exn_store" (func $__wbindgen_exn_store))
+  (@custom "target_features" (after code) "\02+\0fmutable-globals+\08sign-ext")
+)
+