Correctly handle tracebackhide for chained exceptions (#10772)

Author: Felhof

AUTHORS

@@ -128,6 +128,7 @@ Erik M. Bray
 Evan Kepner
 Fabien Zarifian
 Fabio Zadrozny
+Felix Hofstätter
 Felix Nieuwenhuizen
 Feng Ma
 Florian Bruhin

changelog/1904.bugfix.rst

@@ -0,0 +1 @@
+Correctly handle ``__tracebackhide__`` for chained exceptions.

src/_pytest/_code/code.py

@@ -411,13 +411,13 @@ def filter(
         """
         return Traceback(filter(fn, self), self._excinfo)
 
-    def getcrashentry(self) -> TracebackEntry:
+    def getcrashentry(self) -> Optional[TracebackEntry]:
         """Return last non-hidden traceback entry that lead to the exception of a traceback."""
         for i in range(-1, -len(self) - 1, -1):
             entry = self[i]
             if not entry.ishidden():
                 return entry
-        return self[-1]
+        return None
 
     def recursionindex(self) -> Optional[int]:
         """Return the index of the frame/TracebackEntry where recursion originates if
@@ -602,11 +602,13 @@ def errisinstance(
         """
         return isinstance(self.value, exc)
 
-    def _getreprcrash(self) -> "ReprFileLocation":
+    def _getreprcrash(self) -> Optional["ReprFileLocation"]:
         exconly = self.exconly(tryshort=True)
         entry = self.traceback.getcrashentry()
-        path, lineno = entry.frame.code.raw.co_filename, entry.lineno
-        return ReprFileLocation(path, lineno + 1, exconly)
+        if entry:
+            path, lineno = entry.frame.code.raw.co_filename, entry.lineno
+            return ReprFileLocation(path, lineno + 1, exconly)
+        return None
 
     def getrepr(
         self,
@@ -942,18 +944,23 @@ def repr_excinfo(
                     )
                 else:
                     reprtraceback = self.repr_traceback(excinfo_)
-                reprcrash: Optional[ReprFileLocation] = (
-                    excinfo_._getreprcrash() if self.style != "value" else None
-                )
+
+                # will be None if all traceback entries are hidden
+                reprcrash: Optional[ReprFileLocation] = excinfo_._getreprcrash()
+                if reprcrash:
+                    if self.style == "value":
+                        repr_chain += [(reprtraceback, None, descr)]
+                    else:
+                        repr_chain += [(reprtraceback, reprcrash, descr)]
             else:
                 # Fallback to native repr if the exception doesn't have a traceback:
                 # ExceptionInfo objects require a full traceback to work.
                 reprtraceback = ReprTracebackNative(
                     traceback.format_exception(type(e), e, None)
                 )
                 reprcrash = None
+                repr_chain += [(reprtraceback, reprcrash, descr)]
 
-            repr_chain += [(reprtraceback, reprcrash, descr)]
             if e.__cause__ is not None and self.chain:
                 e = e.__cause__
                 excinfo_ = (
@@ -1044,7 +1051,7 @@ def toterminal(self, tw: TerminalWriter) -> None:
 @dataclasses.dataclass(eq=False)
 class ReprExceptionInfo(ExceptionRepr):
     reprtraceback: "ReprTraceback"
-    reprcrash: "ReprFileLocation"
+    reprcrash: Optional["ReprFileLocation"]
 
     def toterminal(self, tw: TerminalWriter) -> None:
         self.reprtraceback.toterminal(tw)

src/_pytest/reports.py

@@ -347,6 +347,10 @@ def from_item_and_call(cls, item: Item, call: "CallInfo[None]") -> "TestReport":
             elif isinstance(excinfo.value, skip.Exception):
                 outcome = "skipped"
                 r = excinfo._getreprcrash()
+                if r is None:
+                    raise ValueError(
+                        "There should always be a traceback entry for skipping a test."
+                    )
                 if excinfo.value._use_item_location:
                     path, line = item.reportinfo()[:2]
                     assert line is not None

testing/code/test_excinfo.py

@@ -294,6 +294,7 @@ def f():
         excinfo = pytest.raises(ValueError, f)
         tb = excinfo.traceback
         entry = tb.getcrashentry()
+        assert entry is not None
         co = _pytest._code.Code.from_function(h)
         assert entry.frame.code.path == co.path
         assert entry.lineno == co.firstlineno + 1
@@ -311,10 +312,7 @@ def f():
         excinfo = pytest.raises(ValueError, f)
         tb = excinfo.traceback
         entry = tb.getcrashentry()
-        co = _pytest._code.Code.from_function(g)
-        assert entry.frame.code.path == co.path
-        assert entry.lineno == co.firstlineno + 2
-        assert entry.frame.code.name == "g"
+        assert entry is None
 
 
 def test_excinfo_exconly():

testing/test_tracebackhide.py

@@ -0,0 +1,25 @@
+def test_tbh_chained(testdir):
+    """Ensure chained exceptions whose frames contain "__tracebackhide__" are not shown (#1904)."""
+    p = testdir.makepyfile(
+        """
+        import pytest
+
+        def f1():
+            __tracebackhide__ = True
+            try:
+                return f1.meh
+            except AttributeError:
+                pytest.fail("fail")
+
+        @pytest.fixture
+        def fix():
+            f1()
+
+
+        def test(fix):
+            pass
+        """
+    )
+    result = testdir.runpytest(str(p))
+    assert "'function' object has no attribute 'meh'" not in result.stdout.str()
+    assert result.ret == 1