diff --git a/.circleci/config.yml b/.circleci/config.yml
new file mode 100644
index 0000000..5e1f035
--- /dev/null
+++ b/.circleci/config.yml
@@ -0,0 +1,24 @@
+version: '2.1'
+orbs:
+  python: circleci/python@1.1.0
+jobs:
+  build:
+    executor:
+      name: python/default
+      tag: "3.11"
+    steps:
+      - checkout
+      - python/install-packages:
+          pip-dependency-file: requirements.txt
+          pkg-manager: pip
+      - run:
+          name: Test
+          command: |
+            mkdir test-results
+            pytest --junitxml=test-results/junit.xml --verbose --color=yes
+      - store_test_results:
+          path: test-results
+workflows:
+  main:
+    jobs:
+      - build
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..ec914b9
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,4 @@
+pytest
+widlparser
+pyodide-py
+pytest-mypy-testing
diff --git a/tests/test_types.py b/tests/test_types.py
new file mode 100644
index 0000000..b372207
--- /dev/null
+++ b/tests/test_types.py
@@ -0,0 +1,148 @@
+import pytest
+
+from io import StringIO
+from collections.abc import Callable
+
+
+@pytest.mark.mypy_testing
+def type_exception():
+    from js import DOMException
+
+    raise DOMException.new("oops")
+
+
+@pytest.mark.mypy_testing
+def type_xmlhttprequest(url: str) -> StringIO:
+    from js import XMLHttpRequest
+
+    req = XMLHttpRequest.new()
+    req.open("GET", url, False)
+    reveal_type(req.open)
+    req.send()
+    # this were a bit more specific
+    reveal_type(req.response)  # R: Any
+    return StringIO(req.response)
+
+
+@pytest.mark.mypy_testing
+def type_fetch() -> None:
+    from js import fetch
+
+
+@pytest.mark.mypy_testing
+def type_eval():
+    from js import eval
+
+    reveal_type(eval("abc"))  # R: Any
+
+
+@pytest.mark.mypy_testing
+def type_timeout(callback: Callable[[], None], timeout: int):
+    from js import setTimeout, clearTimeout, setInterval, clearInterval
+    from pyodide.ffi import JsProxy
+
+    timeout_retval: int | JsProxy = setTimeout(callable, timeout)
+    clearTimeout(timeout_retval)
+
+    setInterval(callable, timeout)
+    clearInterval(timeout_retval)
+
+
+@pytest.mark.mypy_testing
+def type_object():
+    from js import Object
+
+    a: JsProxy = Object.fromEntries([[1, 2]])
+
+
+@pytest.mark.mypy_testing
+def type_buffer(selenium):
+    from js import Uint8Array, ArrayBuffer
+
+    a = Uint8Array.new(range(10))
+    assert ArrayBuffer.isView(a)
+
+    from tempfile import TemporaryFile
+
+    with TemporaryFile() as f:
+        a.to_file(f)
+        f.seek(0)
+        assert f.read() == a.to_bytes()
+
+    import js
+
+    assert js.Float64Array.BYTES_PER_ELEMENT == 8
+
+
+@pytest.mark.mypy_testing
+def type_json():
+    from js import JSON, Array
+    from pyodide.ffi import to_js
+    import json
+
+    class Pair:
+        __slots__ = ("first", "second")
+
+        def __init__(self, first, second):
+            self.first = first
+            self.second = second
+
+    p1 = Pair(1, 2)
+    p2 = Pair(1, 2)
+    p2.first = p2
+
+    def default_converter(value, convert, cacheConversion):
+        result = Array.new()
+        cacheConversion(value, result)
+        result.push(convert(value.first))
+        result.push(convert(value.second))
+        return result
+
+    p1js = to_js(p1, default_converter=default_converter)
+    p2js = to_js(p2, default_converter=default_converter)
+
+    assert json.loads(JSON.stringify(p1js)) == [1, 2]
+
+
+@pytest.mark.mypy_testing
+def type_document():
+    from js import document
+
+    el = document.createElement("div")
+    assert el.tagName == "DIV"
+    assert bool(el)
+    assert document.body
+    assert not document.body.children
+    document.body.appendChild(el)
+    assert document.body.children
+    assert len(document.body.children) == 1
+    assert document.body.children[0] == el
+    assert repr(document) == "[object HTMLDocument]"
+    assert len(dir(el)) >= 200
+    assert "appendChild" in dir(el)
+
+
+@pytest.mark.mypy_testing
+def type_canvas():
+    from js import document
+
+    canvas = document.createElement("canvas")
+    canvas.id = "canvas"
+    canvas.width = 320
+    canvas.height = 240
+
+    canvas.style.position = "fixed"
+    canvas.style.bottom = "10px"
+    canvas.style.right = "10px"
+
+    gl = canvas.getContext(
+        "webgl2",
+        powerPreference="high-performance",
+        premultipliedAlpha=False,
+        antialias=False,
+        alpha=False,
+        depth=False,
+        stencil=False,
+    )
+    assert document.body
+    document.body.appendChild(canvas)