add tests and fix cov

Author: rmorshea

src/idom/_option.py

@@ -14,24 +14,27 @@ def __init__(
         self,
         name: str,
         default: _O,
-        allow_changes: bool = True,
+        immutable: bool = False,
         validator: Callable[[Any], _O] = lambda x: cast(_O, x),
     ) -> None:
         self.name = name
         self._default = default
-        self._allow_changes = allow_changes
+        self._immutable = immutable
         self._validator = validator
         self._value = validator(os.environ.get(name, default))
 
     def get(self) -> _O:
         return self._value
 
     def set(self, new: _O) -> _O:
-        if not self._allow_changes:
-            raise ValueError(f"{self.name} cannot be modified.")
+        if self._immutable:
+            raise TypeError(f"{self} cannot be modified after initial load.")
         old = self._value
         self._value = self._validator(new)
         return old
 
     def reset(self) -> _O:
         return self.set(self._default)
+
+    def __repr__(self) -> str:
+        return f"Option(name={self.name!r}, value={self._value!r})"

src/idom/config.py

@@ -6,7 +6,7 @@
 IDOM_DEBUG_MODE = _option.Option(
     "IDOM_DEBUG_MODE",
     default=False,
-    allow_changes=False,
+    immutable=True,
     validator=lambda x: bool(int(x)),
 )
 """Turn on/off debug mode"""

src/idom/server/flask.py

@@ -241,7 +241,9 @@ def run_send() -> None:
             if value is None:
                 stop.set()
                 break
-            dispatch_thread_info.dispatch_loop.call_soon_threadsafe(
+            # BUG: https://github.com/nedbat/coveragepy/issues/1012
+            # Coverage isn't able to support concurrency coverage for both threading and gevent
+            dispatch_thread_info.dispatch_loop.call_soon_threadsafe(  # pragma: no cover
                 dispatch_thread_info.async_recv_queue.put_nowait, value
             )
     finally:
@@ -273,7 +275,8 @@ def update_environ(self) -> None:
         This includes getting the correct server name and port.
         """
         super().update_environ()
-        # BUG: for some reason coverage doesn't seem to think this line is covered
+        # BUG: https://github.com/nedbat/coveragepy/issues/1012
+        # Coverage isn't able to support concurrency coverage for both threading and gevent
         self._before_first_request_callback()  # pragma: no cover
 
 

tests/test__option.py

@@ -0,0 +1,54 @@
+import os
+from unittest import mock
+
+import pytest
+
+from idom._option import Option
+
+
+def test_option_repr():
+    opt = Option("A_FAKE_OPTION", "some-value")
+    assert repr(opt) == "Option(name='A_FAKE_OPTION', value='some-value')"
+
+
+@mock.patch.dict(os.environ, {"A_FAKE_OPTION": "value-from-environ"})
+def test_option_from_os_environ():
+    opt = Option("A_FAKE_OPTION", "default-value")
+    assert opt.get() == "value-from-environ"
+
+
+def test_option_from_default():
+    opt = Option("A_FAKE_OPTION", "default-value")
+    assert opt.get() == "default-value"
+
+
+@mock.patch.dict(os.environ, {"A_FAKE_OPTION": "1"})
+def test_option_validator():
+    opt = Option("A_FAKE_OPTION", False, validator=lambda x: bool(int(x)))
+
+    assert opt.get() is True
+
+    opt.set("0")
+    assert opt.get() is False
+
+    with pytest.raises(ValueError, match="invalid literal for int"):
+        opt.set("not-an-int")
+
+
+def test_immutable_option():
+    opt = Option("A_FAKE_OPTION", "default-value", immutable=True)
+    with pytest.raises(TypeError, match="cannot be modified after initial load"):
+        opt.set("a-new-value")
+
+
+def test_option_reset():
+    opt = Option("A_FAKE_OPTION", "default-value")
+    opt.set("a-new-value")
+    assert opt.get() == "a-new-value"
+    opt.reset()
+    assert opt.get() == "default-value"
+
+
+def test_option_set_returns_last_value():
+    opt = Option("A_FAKE_OPTION", "default-value")
+    assert opt.set("a-new-value") == "default-value"