Replace std::cout with py::print in tests

With this change both C++ and Python write to sys.stdout which resolves
the capture issues noted in #351. Therefore, the related workarounds are
removed.

.appveyor.yml

@@ -29,5 +29,4 @@ install:
 build_script:
 - cmake -A "%CMAKE_ARCH%" -DPYBIND11_WERROR=ON
 - set MSBuildLogger="C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
-- set PYTEST_ADDOPTS="-s"  # workaround for pytest capture issue, see #351
 - cmake --build . --config Release --target pytest -- /v:m /logger:%MSBuildLogger%

tests/conftest.py

@@ -70,20 +70,12 @@ class Capture(object):
         self.out = ""
         self.err = ""
 
-    def _flush(self):
-        """Workaround for issues on Windows: to be removed after tests get py::print"""
-        sys.stdout.flush()
-        os.fsync(sys.stdout.fileno())
-        sys.stderr.flush()
-        os.fsync(sys.stderr.fileno())
-        return self.capfd.readouterr()
-
     def __enter__(self):
-        self._flush()
+        self.capfd.readouterr()
         return self
 
     def __exit__(self, *_):
-        self.out, self.err = self._flush()
+        self.out, self.err = self.capfd.readouterr()
 
     def __eq__(self, other):
         a = Output(self.out)

tests/constructor_stats.h

@@ -200,14 +200,17 @@ template <class T, typename... Values> void track_values(T *, Values &&...values
     ConstructorStats::get<T>().value(std::forward<Values>(values)...);
 }
 
-inline void print_constr_details_more() { std::cout << std::endl; }
+/// Don't cast pointers to Python, print them as strings
-template <typename Head, typename... Tail> void print_constr_details_more(const Head &head, Tail &&...tail) {
+inline const char *format_ptrs(const char *p) { return p; }
-    std::cout << " " << head;
+template <typename T>
-    print_constr_details_more(std::forward<Tail>(tail)...);
+py::str format_ptrs(T *p) { return "{:#x}"_s.format(reinterpret_cast<std::uintptr_t>(p)); }
-}
+template <typename T>
-template <class T, typename... Output> void print_constr_details(T *inst, const std::string &action, Output &&...output) {
+auto format_ptrs(T &&x) -> decltype(std::forward<T>(x)) { return std::forward<T>(x); }
-    std::cout << "### " << py::type_id<T>() << " @ " << inst << " " << action;
+
-    print_constr_details_more(std::forward<Output>(output)...);
+template <class T, typename... Output>
+void print_constr_details(T *inst, const std::string &action, Output &&...output) {
+    py::print("###", py::type_id<T>(), "@", format_ptrs(inst), action,
+              format_ptrs(std::forward<Output>(output))...);
 }
 
 // Verbose versions of the above:

tests/pybind11_tests.h

@@ -1,12 +1,8 @@
 #pragma once
 #include <pybind11/pybind11.h>
-#include <iostream>
 #include <functional>
 #include <list>
 
-using std::cout;
-using std::endl;
-
 namespace py = pybind11;
 using namespace pybind11::literals;
 

tests/test_issues.cpp

@@ -121,14 +121,14 @@ void init_issues(py::module &m) {
     // classes that were not extended on the Python side
     struct A {
         virtual ~A() {}
-        virtual void f() { std::cout << "A.f()" << std::endl; }
+        virtual void f() { py::print("A.f()"); }
     };
 
     struct PyA : A {
-        PyA() { std::cout << "PyA.PyA()" << std::endl; }
+        PyA() { py::print("PyA.PyA()"); }
 
         void f() override {
-            std::cout << "PyA.f()" << std::endl;
+            py::print("PyA.f()");
             PYBIND11_OVERLOAD(void, A, f);
         }
     };
@@ -177,7 +177,7 @@ void init_issues(py::module &m) {
     class MoveIssue1 {
     public:
         MoveIssue1(int v) : v{v} {}
-        MoveIssue1(const MoveIssue1 &c) { std::cerr << "copy ctor\n"; v=c.v; }
+        MoveIssue1(const MoveIssue1 &c) { v = c.v; }
         MoveIssue1(MoveIssue1 &&) = delete;
         int v;
     };

tests/test_keep_alive.cpp

@@ -12,14 +12,14 @@
 
 class Child {
 public:
-    Child() { std::cout << "Allocating child." << std::endl; }
+    Child() { py::print("Allocating child."); }
-    ~Child() { std::cout << "Releasing child." << std::endl; }
+    ~Child() { py::print("Releasing child."); }
 };
 
 class Parent {
 public:
-    Parent() { std::cout << "Allocating parent." << std::endl; }
+    Parent() { py::print("Allocating parent."); }
-    ~Parent() { std::cout << "Releasing parent." << std::endl; }
+    ~Parent() { py::print("Releasing parent."); }
     void addChild(Child *) { }
     Child *returnChild() { return new Child(); }
     Child *returnNullChild() { return nullptr; }

tests/test_numpy_vectorize.cpp

@@ -12,7 +12,7 @@
 #include <pybind11/numpy.h>
 
 double my_func(int x, float y, double z) {
-    std::cout << "my_func(x:int=" << x << ", y:float=" << y << ", z:float=" << z << ")" << std::endl;
+    py::print("my_func(x:int={}, y:float={:.0f}, z:float={:.0f})"_s.format(x, y, z));
     return (float) x*y*z;
 }
 

tests/test_python_types.cpp

@@ -60,7 +60,7 @@ public:
     py::list get_list() {
         py::list list;
         list.append(py::str("value"));
-        cout << "Entry at positon 0: " << py::object(list[0]) << endl;
+        py::print("Entry at position 0:", py::object(list[0]));
         list[0] = py::str("overwritten");
         return list;
     }
@@ -80,42 +80,39 @@ public:
     /* Easily iterate over a dictionary using a C++11 range-based for loop */
     void print_dict(py::dict dict) {
         for (auto item : dict)
-            std::cout << "key: " << item.first << ", value=" << item.second << std::endl;
+            py::print("key: {}, value={}"_s.format(item.first, item.second));
     }
 
     /* Easily iterate over a set using a C++11 range-based for loop */
     void print_set(py::set set) {
         for (auto item : set)
-            std::cout << "key: " << item << std::endl;
+            py::print("key:", item);
     }
 
     /* Easily iterate over a list using a C++11 range-based for loop */
     void print_list(py::list list) {
         int index = 0;
         for (auto item : list)
-            std::cout << "list item " << index++ << ": " << item << std::endl;
+            py::print("list item {}: {}"_s.format(index++, item));
     }
 
     /* STL data types (such as maps) are automatically casted from Python */
     void print_dict_2(const std::map<std::string, std::string> &dict) {
         for (auto item : dict)
-            std::cout << "key: " << item.first << ", value=" << item.second << std::endl;
+            py::print("key: {}, value={}"_s.format(item.first, item.second));
     }
 
     /* STL data types (such as sets) are automatically casted from Python */
     void print_set_2(const std::set<std::string> &set) {
         for (auto item : set)
-            std::cout << "key: " << item << std::endl;
+            py::print("key:", item);
     }
 
     /* STL data types (such as vectors) are automatically casted from Python */
     void print_list_2(std::vector<std::wstring> &list) {
-#ifdef _WIN32 /* Can't easily mix cout and wcout on Windows */
-        _setmode(_fileno(stdout), _O_TEXT);
-#endif
         int index = 0;
         for (auto item : list)
-            std::wcout << L"list item " << index++ << L": " << item << std::endl;
+            py::print("list item {}: {}"_s.format(index++, item));
     }
 
     /* pybind automatically translates between C++11 and Python tuples */
@@ -132,7 +129,7 @@ public:
     void print_array(std::array<std::string, 2> &array) {
         int index = 0;
         for (auto item : array)
-            std::cout << "array item " << index++ << ": " << item << std::endl;
+            py::print("array item {}: {}"_s.format(index++, item));
     }
 
     void throw_exception() {
@@ -156,8 +153,8 @@ public:
     }
 
     void test_print(const py::object& obj) {
-        std::cout << obj.str() << std::endl;
+        py::print(obj.str());
-        std::cout << obj.repr() << std::endl;
+        py::print(obj.repr());
     }
 
     static int value;

tests/test_python_types.py

@@ -59,7 +59,7 @@ def test_instance(capture):
         list_result.append('value2')
         instance.print_list(list_result)
     assert capture.unordered == """
-        Entry at positon 0: value
+        Entry at position 0: value
         list item 0: overwritten
         list item 1: value2
     """

tests/test_smart_ptr.cpp

@@ -97,25 +97,25 @@ std::shared_ptr<MyObject2> make_myobject2_2() { return std::make_shared<MyObject
 MyObject3 *make_myobject3_1() { return new MyObject3(8); }
 std::shared_ptr<MyObject3> make_myobject3_2() { return std::make_shared<MyObject3>(9); }
 
-void print_object_1(const Object *obj) { std::cout << obj->toString() << std::endl; }
+void print_object_1(const Object *obj) { py::print(obj->toString()); }
-void print_object_2(ref<Object> obj) { std::cout << obj->toString() << std::endl; }
+void print_object_2(ref<Object> obj) { py::print(obj->toString()); }
-void print_object_3(const ref<Object> &obj) { std::cout << obj->toString() << std::endl; }
+void print_object_3(const ref<Object> &obj) { py::print(obj->toString()); }
-void print_object_4(const ref<Object> *obj) { std::cout << (*obj)->toString() << std::endl; }
+void print_object_4(const ref<Object> *obj) { py::print((*obj)->toString()); }
 
-void print_myobject1_1(const MyObject1 *obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject1_1(const MyObject1 *obj) { py::print(obj->toString()); }
-void print_myobject1_2(ref<MyObject1> obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject1_2(ref<MyObject1> obj) { py::print(obj->toString()); }
-void print_myobject1_3(const ref<MyObject1> &obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject1_3(const ref<MyObject1> &obj) { py::print(obj->toString()); }
-void print_myobject1_4(const ref<MyObject1> *obj) { std::cout << (*obj)->toString() << std::endl; }
+void print_myobject1_4(const ref<MyObject1> *obj) { py::print((*obj)->toString()); }
 
-void print_myobject2_1(const MyObject2 *obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject2_1(const MyObject2 *obj) { py::print(obj->toString()); }
-void print_myobject2_2(std::shared_ptr<MyObject2> obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject2_2(std::shared_ptr<MyObject2> obj) { py::print(obj->toString()); }
-void print_myobject2_3(const std::shared_ptr<MyObject2> &obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject2_3(const std::shared_ptr<MyObject2> &obj) { py::print(obj->toString()); }
-void print_myobject2_4(const std::shared_ptr<MyObject2> *obj) { std::cout << (*obj)->toString() << std::endl; }
+void print_myobject2_4(const std::shared_ptr<MyObject2> *obj) { py::print((*obj)->toString()); }
 
-void print_myobject3_1(const MyObject3 *obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject3_1(const MyObject3 *obj) { py::print(obj->toString()); }
-void print_myobject3_2(std::shared_ptr<MyObject3> obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject3_2(std::shared_ptr<MyObject3> obj) { py::print(obj->toString()); }
-void print_myobject3_3(const std::shared_ptr<MyObject3> &obj) { std::cout << obj->toString() << std::endl; }
+void print_myobject3_3(const std::shared_ptr<MyObject3> &obj) { py::print(obj->toString()); }
-void print_myobject3_4(const std::shared_ptr<MyObject3> *obj) { std::cout << (*obj)->toString() << std::endl; }
+void print_myobject3_4(const std::shared_ptr<MyObject3> *obj) { py::print((*obj)->toString()); }
 
 test_initializer smart_ptr([](py::module &m) {
     py::class_<Object, ref<Object>> obj(m, "Object");

tests/test_virtual_functions.cpp

@@ -20,8 +20,8 @@ public:
     ~ExampleVirt() { print_destroyed(this); }
 
     virtual int run(int value) {
-        std::cout << "Original implementation of ExampleVirt::run(state=" << state
+        py::print("Original implementation of "
-                  << ", value=" << value << ")" << std::endl;
+                  "ExampleVirt::run(state={}, value={})"_s.format(state, value));
         return state + value;
     }