DPCTLSyclInterface should avoid functions that print to std::cout (#542)

* use GetDeviceInfoStr

dpctl.SyclDevice.print_device_info gets CString from DPCTL-CAPI and
prints it using Python's stream.

* Used pytest stream capture to test q.print_device_info

Author: oleksandr-pavlyk

dpctl/_backend.pxd

@@ -207,7 +207,7 @@ cdef extern from "dpctl_sycl_device_manager.h":
         const DPCTLSyclDeviceRef DRef,
         int device_identifier)
     cdef size_t DPCTLDeviceMgr_GetNumDevices(int device_identifier)
-    cdef void DPCTLDeviceMgr_PrintDeviceInfo(const DPCTLSyclDeviceRef DRef)
+    cdef const char * DPCTLDeviceMgr_GetDeviceInfoStr(const DPCTLSyclDeviceRef DRef)
     cdef DPCTLSyclContextRef DPCTLDeviceMgr_GetCachedContext(
         const DPCTLSyclDeviceRef DRef)
     cdef int64_t DPCTLDeviceMgr_GetRelativeId(const DPCTLSyclDeviceRef DRef)

dpctl/_sycl_device.pyx

@@ -65,10 +65,10 @@ from ._backend cimport (  # noqa: E211
     DPCTLDevice_IsCPU,
     DPCTLDevice_IsGPU,
     DPCTLDevice_IsHost,
+    DPCTLDeviceMgr_GetDeviceInfoStr,
     DPCTLDeviceMgr_GetDevices,
     DPCTLDeviceMgr_GetPositionInDevices,
     DPCTLDeviceMgr_GetRelativeId,
-    DPCTLDeviceMgr_PrintDeviceInfo,
     DPCTLDeviceSelector_Delete,
     DPCTLDeviceSelector_Score,
     DPCTLDeviceVector_Delete,
@@ -286,7 +286,12 @@ cdef class SyclDevice(_SyclDevice):
     def print_device_info(self):
         """ Print information about the SYCL device.
         """
-        DPCTLDeviceMgr_PrintDeviceInfo(self._device_ref)
+        cdef const char * info_str = DPCTLDeviceMgr_GetDeviceInfoStr(
+            self._device_ref
+        )
+        py_info = <bytes> info_str
+        DPCTLCString_Delete(info_str)
+        print(py_info.decode("utf-8"))
 
     cdef DPCTLSyclDeviceRef get_device_ref(self):
         """ Returns the DPCTLSyclDeviceRef pointer for this class.

dpctl/tests/test_sycl_queue.py

@@ -17,6 +17,9 @@
 """ Defines unit test cases for the SyclQueue class.
 """
 
+import ctypes
+import sys
+
 import pytest
 
 import dpctl
@@ -395,22 +398,22 @@ def test_hashing_of_queue():
     assert queue_dict
 
 
-def test_channeling_device_properties():
+def test_channeling_device_properties(capsys):
     try:
         q = dpctl.SyclQueue()
         dev = q.sycl_device
     except dpctl.SyclQueueCreationError:
         pytest.fail("Failed to create device from default selector")
-    import io
-    from contextlib import redirect_stdout
-
-    f1 = io.StringIO()
-    with redirect_stdout(f1):
-        q.print_device_info()  # should execute without raising
-    f2 = io.StringIO()
-    with redirect_stdout(f2):
-        dev.print_device_info()
-    assert f1.getvalue() == f2.getvalue(), "Mismatch in print_device_info"
+
+    q.print_device_info()  # should execute without raising
+    q_captured = capsys.readouterr()
+    q_output = q_captured.out
+    dev.print_device_info()
+    d_captured = capsys.readouterr()
+    d_output = d_captured.out
+    assert q_output, "No output captured"
+    assert q_output == d_output, "Mismatch in print_device_info"
+    assert q_captured.err == "" and d_captured.err == ""
     for pr in ["backend", "name", "driver_version"]:
         assert getattr(q, pr) == getattr(
             dev, pr
@@ -468,9 +471,6 @@ def test_queue_capsule():
 
 
 def test_cpython_api():
-    import ctypes
-    import sys
-
     q = dpctl.SyclQueue()
     mod = sys.modules[q.__class__.__module__]
     # get capsule storign get_context_ref function ptr