Added python tests

corelib/test/test_python_interface.cpp

@@ -0,0 +1,100 @@
+// Tests for PythonInterface and its companion getPythonTraceback() helper.
+// Mostly regression coverage for the NULL-safety fixes in getPythonTraceback
+// (early-return on no exception, Py_None substitution for missing fetch
+// components, NULL-safe DECREFs).
+//
+// The whole file is a no-op when rtabmap is built without Python -- the
+// CMakeLists.txt only registers it under WITH_PYTHON AND Python3_FOUND, and
+// a defensive #ifdef matches that.
+
+#include <gtest/gtest.h>
+#include <rtabmap/core/Version.h>
+
+#ifdef RTABMAP_PYTHON
+
+#include <rtabmap/core/PythonInterface.h>
+
+#include <pybind11/embed.h>
+#include <Python.h>
+
+#include <string>
+
+using namespace rtabmap;
+
+namespace {
+
+// All tests need a live interpreter; instance() lazily initializes it.
+class PythonInterfaceTest : public ::testing::Test
+{
+protected:
+	void SetUp() override
+	{
+		PythonInterface::instance("test_python_interface");
+	}
+};
+
+}  // namespace
+
+// instance() must return the same object every call and never re-initialize
+// the embedded interpreter. Pinning this so any future refactor can't
+// accidentally regress to "construct a new interpreter per call" (which
+// pybind11's scoped_interpreter does not support in the same process).
+TEST_F(PythonInterfaceTest, InstanceIsSingleton)
+{
+	PythonInterface & a = PythonInterface::instance("test_a");
+	PythonInterface & b = PythonInterface::instance("test_b");
+	EXPECT_EQ(&a, &b);
+}
+
+// No active Python exception -> the helper returns a clear sentinel instead
+// of crashing inside Py_BuildValue("OOO", NULL, NULL, NULL). The sentinel
+// makes it obvious in logs that there was nothing useful to report.
+TEST_F(PythonInterfaceTest, TracebackEmptyWhenNoException)
+{
+	pybind11::gil_scoped_acquire acquire;
+	PyErr_Clear();
+	ASSERT_FALSE(PyErr_Occurred());
+
+	EXPECT_EQ("<no python exception set>", getPythonTraceback());
+}
+
+// With a real exception set, the formatter returns a non-empty string that
+// includes the original message. getPythonTraceback consumes the exception
+// (PyErr_Fetch clears it), so PyErr_Occurred is false afterward.
+TEST_F(PythonInterfaceTest, TracebackFormattedAfterException)
+{
+	pybind11::gil_scoped_acquire acquire;
+	PyErr_Clear();
+	PyErr_SetString(PyExc_RuntimeError, "test error message");
+
+	const std::string trace = getPythonTraceback();
+	EXPECT_FALSE(trace.empty());
+	EXPECT_NE("<no python exception set>", trace);
+	EXPECT_NE(std::string::npos, trace.find("test error message"));
+	EXPECT_FALSE(PyErr_Occurred());
+}
+
+// Repeated calls on the no-exception path must stay stable. The original
+// crashes (Py_DECREF on NULL outStr, Py_BuildValue on NULL slots) surfaced
+// non-deterministically after several invocations -- this loop would have
+// reliably tripped them.
+TEST_F(PythonInterfaceTest, RepeatedCallsAreStable)
+{
+	pybind11::gil_scoped_acquire acquire;
+	for(int i = 0; i < 25; ++i)
+	{
+		PyErr_Clear();
+		EXPECT_EQ("<no python exception set>", getPythonTraceback());
+	}
+
+	// Same robustness check with an exception each time.
+	for(int i = 0; i < 25; ++i)
+	{
+		PyErr_SetString(PyExc_ValueError, "boom");
+		const std::string trace = getPythonTraceback();
+		EXPECT_FALSE(trace.empty());
+		EXPECT_NE("<no python exception set>", trace);
+	}
+}
+
+#endif  // RTABMAP_PYTHON