refactor: move kwargs resolution to render-time + cleanup (#594)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

tests/test_expression.py

@@ -0,0 +1,60 @@
+"""Catch-all for tests that use template tags and don't fit other files"""
+
+from typing import Dict
+
+from django.template import Context, Template
+from django.template.base import Parser
+
+from django_components.expression import safe_resolve_dict, safe_resolve_list
+
+from .django_test_setup import setup_test_config
+from .testutils import BaseTestCase
+
+setup_test_config({"autodiscover": False})
+
+
+engine = Template("").engine
+default_parser = Parser("", engine.template_libraries, engine.template_builtins)
+
+
+def make_context(d: Dict):
+    ctx = Context(d)
+    ctx.template = Template("")
+    return ctx
+
+
+#######################
+# TESTS
+#######################
+
+
+class ResolveTests(BaseTestCase):
+    def test_safe_resolve(self):
+        expr = default_parser.compile_filter("var_abc")
+
+        ctx = make_context({"var_abc": 123})
+        self.assertEqual(
+            expr.resolve(ctx),
+            123,
+        )
+
+        ctx2 = make_context({"var_xyz": 123})
+        self.assertEqual(expr.resolve(ctx2), "")
+
+    def test_safe_resolve_list(self):
+        exprs = [default_parser.compile_filter(f"var_{char}") for char in "abc"]
+
+        ctx = make_context({"var_a": 123, "var_b": [{}, {}]})
+        self.assertEqual(
+            safe_resolve_list(ctx, exprs),
+            [123, [{}, {}], ""],
+        )
+
+    def test_safe_resolve_dict(self):
+        exprs = {char: default_parser.compile_filter(f"var_{char}") for char in "abc"}
+
+        ctx = make_context({"var_a": 123, "var_b": [{}, {}]})
+        self.assertEqual(
+            safe_resolve_dict(ctx, exprs),
+            {"a": 123, "b": [{}, {}], "c": ""},
+        )