Add unit test for namespaces

tests/test_namespaces.py

@@ -0,0 +1,39 @@
+from shiny._namespaces import namespace_context, resolve_id
+
+
+def test_namespaces():
+    outer = resolve_id("outer")
+    assert outer == "outer"
+
+    with namespace_context(outer):
+        # Check if the namespace_context ("outer") is respected during resolve_id
+        inner = resolve_id("inner")
+        assert inner == "outer-inner"
+
+        # You can also use a ResolvedId as a namespace just by calling it with an id str
+        assert outer("inner") == "outer-inner"
+
+        # If an id is already resolved (based on ResolvedId class), resolving it further
+        # does nothing
+        assert resolve_id(outer) == "outer"
+
+        # When namespace contexts are stacked, inner one wins
+        with namespace_context(inner):
+            assert resolve_id("inmost") == "outer-inner-inmost"
+
+        # Namespace contexts nest with existing context when string is used
+        with namespace_context("inner"):
+            assert resolve_id("inmost") == "outer-inner-inmost"
+
+        # Re-installing the same context as is already in place
+        with namespace_context(outer):
+            assert resolve_id("inmost") == "outer-inmost"
+
+        # You can remove the context with None or ""
+        with namespace_context(None):
+            assert resolve_id("foo") == "foo"
+        with namespace_context(""):
+            assert resolve_id("foo") == "foo"
+
+        # Check that this still works after another context was installed/removed
+        assert resolve_id("inner") == "outer-inner"