👌 Fail and emit warning on filters that do not return a boolean result

docs/changelog.rst

@@ -8,6 +8,12 @@ License
 
 .. include:: ../LICENSE
 
+Unreleased
+----------
+
+* 👌 Fail and emit warning on filters that do not return a boolean result
+  (`#964 <https://github.com/useblocks/sphinx-needs/pull/964>`_)
+
 
 2.0.0
 -----

docs/directives/need.rst

@@ -267,14 +267,14 @@ are representing some kind of a diagram.
 .. code-block:: rst
 
    .. needtable::
-      :filter: arch
+      :filter: bool(arch)
       :style: table
       :columns: id, type, title
 
 |out|
 
 .. needtable::
-   :filter: arch
+   :filter: bool(arch)
    :style: table
    :columns: id, type, title
 

sphinx_needs/filter_common.py

@@ -354,6 +354,10 @@ def filter_needs(
     return found_needs
 
 
+def need_search(*args: Any, **kwargs: Any) -> bool:
+    return re.search(*args, **kwargs) is not None
+
+
 @measure_time("filtering")
 def filter_single_need(
     need: NeedsInfoType,
@@ -385,15 +389,19 @@ def filter_single_need(
     # Get needs external filter data and merge to filter_context
     filter_context.update(config.filter_data)
 
-    filter_context["search"] = re.search
+    filter_context["search"] = need_search
     result = False
     try:
         # Set filter_context as globals and not only locals in eval()!
         # Otherwise, the vars not be accessed in list comprehensions.
         if filter_compiled:
-            result = bool(eval(filter_compiled, filter_context))
+            result = eval(filter_compiled, filter_context)
         else:
-            result = bool(eval(filter_string, filter_context))
+            result = eval(filter_string, filter_context)
+        if not isinstance(result, bool):
+            raise NeedsInvalidFilter(
+                f"Filter did not evaluate to a boolean, instead {type(result)}: {result}"
+            )
     except Exception as e:
         raise NeedsInvalidFilter(f"Filter {filter_string!r} not valid. Error: {e}.")
     return result

tests/doc_test/filter_doc/index.rst

@@ -51,6 +51,9 @@ Testing bad filters
 .. needfilter::
    :filter: xxx
 
+.. needfilter::
+   :filter: 1
+
 .. needlist::
    :filter: yyy
 

tests/test_filter.py

@@ -20,8 +20,9 @@ def test_filter_build_html(test_app):
         print(w)
     assert warnings == [
         "srcdir/index.rst:51: WARNING: Filter 'xxx' not valid. Error: name 'xxx' is not defined. [needs.filter]",
-        "srcdir/index.rst:54: WARNING: Filter 'yyy' not valid. Error: name 'yyy' is not defined. [needs.filter]",
-        "srcdir/index.rst:57: WARNING: Filter 'zzz' not valid. Error: name 'zzz' is not defined. [needs.filter]",
+        "srcdir/index.rst:54: WARNING: Filter '1' not valid. Error: Filter did not evaluate to a boolean, instead <class 'int'>: 1. [needs.filter]",
+        "srcdir/index.rst:57: WARNING: Filter 'yyy' not valid. Error: name 'yyy' is not defined. [needs.filter]",
+        "srcdir/index.rst:60: WARNING: Filter 'zzz' not valid. Error: name 'zzz' is not defined. [needs.filter]",
     ]
 
     html = Path(app.outdir, "index.html").read_text()