1 files changed, 53 insertions, 0 deletions

diff --git a/tests/test_typestubs.py b/tests/test_typestubs.py
new file mode 100644
index 0000000..6a8d75f
--- /dev/null
+++ b/tests/test_typestubs.py
@@ -0,0 +1,53 @@
+import ast
+import re
+
+
+def read_stubfile():
+    with open("adblock/adblock.pyi", encoding="utf-8") as file:
+        node = ast.parse(file.read())
+    return node
+
+
+def get_functions_and_methods(node):
+    functions = [n for n in node.body if isinstance(n, ast.FunctionDef)]
+    classes = [n for n in node.body if isinstance(n, ast.ClassDef)]
+
+    methods = {}
+    for c in classes:
+        methods[c.name] = [n for n in c.body if isinstance(n, ast.FunctionDef)]
+
+    return functions, methods
+
+
+def pattern_exists_in_file(filename, regex):
+    """
+    Checks if the given regex is present in the given file
+    """
+    with open(filename, "r", encoding="utf-8") as f:
+        for line in f:
+            if re.search(regex, line):
+                return True
+    return False
+
+
+def test_functions_and_methods_exist_in_rust():
+    """
+    Check that for each of the functions and methods present in the Python
+    typestub file, there is a line in `src/lib.rs` containing a matching
+    definition. Since we're doing a naive grep search, without access to the
+    Rust AST, there may be false negatives.
+    """
+    stubfile_node = read_stubfile()
+    functions, methods = get_functions_and_methods(stubfile_node)
+
+    methods_flattened = []
+    for class_methods in methods.values():
+        methods_flattened += class_methods
+
+    for f in functions + methods_flattened:
+        if f.name.startswith("__"):
+            # Skip dunder methods since their names are the same for every
+            # class, making the test not particularly useful. They are also not
+            # marked `pub` in Rust.
+            continue
+        assert pattern_exists_in_file("src/lib.rs", r"pub fn {}".format(f.name))