fix(python/Context): fix Namespace.get to remember default

Problem: given a Namespace ns, if I want to have a dict field and I do
`d = ns.get("foo", {})` I get a dict, but it doesn't get stored in the
Namespace. So next time I use the same construct to get the dict, I
get a brand new dict.

Fix: Store the default value in the Namespace so the same object gets
returned the next time.

Also add a little debug logging and improvements to repr(Context) that
helped me debug this.

2 files changed, 18 insertions, 3 deletions

diff --git a/templates/python/context.py b/templates/python/context.py
index f7af624..9ecae19 100644
--- a/templates/python/context.py
+++ b/templates/python/context.py
@@ -27,11 +27,12 @@ class Context:
         del self._vars[key]
 
     def __repr__(self):
-        return repr(self._vars)
+        return repr({"vars": self._vars, "namespaces": self._ns})
 
     def declare(self, name):
         if name not in self._ns:
             self._ns[name] = NameSpace(name)
+            logging.debug(f"Context: declared {name}")
         return self._ns[name]
 
 
@@ -44,7 +45,11 @@ class NameSpace:
         return dict(self._dict)
 
     def get(self, key, default=None):
-        return self._dict.get(key, default)
+        if key not in self._dict:
+            if default is None:
+                return None
+            self._dict[key] = default
+        return self._dict[key]
 
     def __setitem__(self, key, value):
         self._dict[key] = value
@@ -57,3 +62,6 @@ class NameSpace:
 
     def __delitem__(self, key):
         del self._dict[key]
+
+    def __repr__(self):
+        return repr(self._dict)
diff --git a/templates/python/context_tests.py b/templates/python/context_tests.py
index ff4e558..d878084 100644
--- a/templates/python/context_tests.py
+++ b/templates/python/context_tests.py
@@ -81,10 +81,17 @@ class ContextNamepaceTests(unittest.TestCase):
         ns["bar"] = "yo"
         self.assertEqual(ns.get("bar", "argh"), "yo")
 
-    def test_gets_with_default(self):
+    def test_get_without_default_doesnt_set(self):
+        ctx = Context()
+        ns = ctx.declare("foo")
+        ns.get("bar")
+        self.assertFalse("bar" in ns)
+
+    def test_gets_with_default_sets_as_well(self):
         ctx = Context()
         ns = ctx.declare("foo")
         self.assertEqual(ns.get("bar", "yo"), "yo")
+        self.assertEqual(ns["bar"], "yo")
 
     def test_does_not_contain_key(self):
         ctx = Context()