From fb2640b82fdf6789d36a8204066695c2cc14ff6a Mon Sep 17 00:00:00 2001
From: Ran Benita <ran@unusedvar.com>
Date: Sun, 28 Jun 2020 18:34:32 +0300
Subject: [PATCH] Stop using ExceptionInfo.errisinstance internally

It does the same as a simple isinstance check, but adds a little layer
of obscurity on top, which the type checker can't penetrate.
---
 src/_pytest/_code/code.py |  7 +++++--
 src/_pytest/main.py       |  2 +-
 src/_pytest/reports.py    |  2 +-
 src/_pytest/runner.py     | 21 ++++++++++++++-------
 src/_pytest/unittest.py   |  4 +---
 5 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/src/_pytest/_code/code.py b/src/_pytest/_code/code.py
index e548bceb7..ab38b204f 100644
--- a/src/_pytest/_code/code.py
+++ b/src/_pytest/_code/code.py
@@ -558,7 +558,10 @@ class ExceptionInfo(Generic[_E]):
     def errisinstance(
         self, exc: Union["Type[BaseException]", Tuple["Type[BaseException]", ...]]
     ) -> bool:
-        """ return True if the exception is an instance of exc """
+        """Return True if the exception is an instance of exc.
+
+        Consider using ``isinstance(excinfo.value, exc)`` instead.
+        """
         return isinstance(self.value, exc)
 
     def _getreprcrash(self) -> "ReprFileLocation":
@@ -804,7 +807,7 @@ class FormattedExcinfo:
         if self.tbfilter:
             traceback = traceback.filter()
 
-        if excinfo.errisinstance(RecursionError):
+        if isinstance(excinfo.value, RecursionError):
             traceback, extraline = self._truncate_recursive_traceback(traceback)
         else:
             extraline = None
diff --git a/src/_pytest/main.py b/src/_pytest/main.py
index 98dabaf87..7e6816506 100644
--- a/src/_pytest/main.py
+++ b/src/_pytest/main.py
@@ -265,7 +265,7 @@ def wrap_session(
                     session.exitstatus = exc.returncode
                 sys.stderr.write("{}: {}\n".format(type(exc).__name__, exc))
             else:
-                if excinfo.errisinstance(SystemExit):
+                if isinstance(excinfo.value, SystemExit):
                     sys.stderr.write("mainloop: caught unexpected SystemExit!\n")
 
     finally:
diff --git a/src/_pytest/reports.py b/src/_pytest/reports.py
index 7aba0b024..186c53ed3 100644
--- a/src/_pytest/reports.py
+++ b/src/_pytest/reports.py
@@ -308,7 +308,7 @@ class TestReport(BaseReport):
             if not isinstance(excinfo, ExceptionInfo):
                 outcome = "failed"
                 longrepr = excinfo
-            elif excinfo.errisinstance(skip.Exception):
+            elif isinstance(excinfo.value, skip.Exception):
                 outcome = "skipped"
                 r = excinfo._getreprcrash()
                 longrepr = (str(r.path), r.lineno, r.message)
diff --git a/src/_pytest/runner.py b/src/_pytest/runner.py
index 8b23cb49e..702380a5b 100644
--- a/src/_pytest/runner.py
+++ b/src/_pytest/runner.py
@@ -215,11 +215,18 @@ def call_and_report(
 
 
 def check_interactive_exception(call: "CallInfo", report: BaseReport) -> bool:
-    return call.excinfo is not None and not (
-        hasattr(report, "wasxfail")
-        or call.excinfo.errisinstance(Skipped)
-        or call.excinfo.errisinstance(bdb.BdbQuit)
-    )
+    """Check whether the call raised an exception that should be reported as
+    interactive."""
+    if call.excinfo is None:
+        # Didn't raise.
+        return False
+    if hasattr(report, "wasxfail"):
+        # Exception was expected.
+        return False
+    if isinstance(call.excinfo.value, (Skipped, bdb.BdbQuit)):
+        # Special control flow exception.
+        return False
+    return True
 
 
 def call_runtest_hook(
@@ -287,7 +294,7 @@ class CallInfo(Generic[_T]):
             result = func()  # type: Optional[_T]
         except BaseException:
             excinfo = ExceptionInfo.from_current()
-            if reraise is not None and excinfo.errisinstance(reraise):
+            if reraise is not None and isinstance(excinfo.value, reraise):
                 raise
             result = None
         # use the perf counter
@@ -325,7 +332,7 @@ def pytest_make_collect_report(collector: Collector) -> CollectReport:
         if unittest is not None:
             # Type ignored because unittest is loaded dynamically.
             skip_exceptions.append(unittest.SkipTest)  # type: ignore
-        if call.excinfo.errisinstance(tuple(skip_exceptions)):
+        if isinstance(call.excinfo.value, tuple(skip_exceptions)):
             outcome = "skipped"
             r_ = collector._repr_failure_py(call.excinfo, "line")
             assert isinstance(r_, ExceptionChainRepr), repr(r_)
diff --git a/src/_pytest/unittest.py b/src/_pytest/unittest.py
index 0e4a31311..bd61726c7 100644
--- a/src/_pytest/unittest.py
+++ b/src/_pytest/unittest.py
@@ -302,9 +302,7 @@ def pytest_runtest_makereport(item: Item, call: CallInfo[None]) -> None:
     if (
         unittest
         and call.excinfo
-        and call.excinfo.errisinstance(
-            unittest.SkipTest  # type: ignore[attr-defined] # noqa: F821
-        )
+        and isinstance(call.excinfo.value, unittest.SkipTest)  # type: ignore[attr-defined]
     ):
         excinfo = call.excinfo
         # let's substitute the excinfo with a pytest.skip one