1 files changed, 135 insertions, 0 deletions
diff --git a/libcxx/test/std/numerics/complex.number/complex.value.ops/arg.pass.cpp b/libcxx/test/std/numerics/complex.number/complex.value.ops/arg.pass.cpp
new file mode 100644
index 00000000000..a7da456b979
--- /dev/null
+++ b/libcxx/test/std/numerics/complex.number/complex.value.ops/arg.pass.cpp
@@ -0,0 +1,135 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <complex>
+
+// template<class T>
+//   T
+//   arg(const complex<T>& x);
+
+#include <complex>
+#include <cassert>
+
+#include "../cases.h"
+
+template <class T>
+void
+test()
+{
+    std::complex<T> z(1, 0);
+    assert(arg(z) == 0);
+}
+
+void test_edges()
+{
+    const double pi = std::atan2(+0., -0.);
+    const unsigned N = sizeof(x) / sizeof(x[0]);
+    for (unsigned i = 0; i < N; ++i)
+    {
+        double r = arg(x[i]);
+        if (std::isnan(x[i].real()) || std::isnan(x[i].imag()))
+            assert(std::isnan(r));
+        else
+        {
+            switch (classify(x[i]))
+            {
+            case zero:
+                if (std::signbit(x[i].real()))
+                {
+                    if (std::signbit(x[i].imag()))
+                        is_about(r, -pi);
+                    else
+                        is_about(r, pi);
+                }
+                else
+                {
+                    assert(std::signbit(x[i].imag()) == std::signbit(r));
+                }
+                break;
+            case non_zero:
+                if (x[i].real() == 0)
+                {
+                    if (x[i].imag() < 0)
+                        is_about(r, -pi/2);
+                    else
+                        is_about(r, pi/2);
+                }
+                else if (x[i].imag() == 0)
+                {
+                    if (x[i].real() < 0)
+                    {
+                        if (std::signbit(x[i].imag()))
+                            is_about(r, -pi);
+                        else
+                            is_about(r, pi);
+                    }
+                    else
+                    {
+                        assert(r == 0);
+                        assert(std::signbit(x[i].imag()) == std::signbit(r));
+                    }
+                }
+                else if (x[i].imag() > 0)
+                    assert(r > 0);
+                else
+                    assert(r < 0);
+                break;
+            case inf:
+                if (std::isinf(x[i].real()) && std::isinf(x[i].imag()))
+                {
+                    if (x[i].real() < 0)
+                    {
+                        if (x[i].imag() > 0)
+                            is_about(r, 0.75 * pi);
+                        else
+                            is_about(r, -0.75 * pi);
+                    }
+                    else
+                    {
+                        if (x[i].imag() > 0)
+                            is_about(r, 0.25 * pi);
+                        else
+                            is_about(r, -0.25 * pi);
+                    }
+                }
+                else if (std::isinf(x[i].real()))
+                {
+                    if (x[i].real() < 0)
+                    {
+                        if (std::signbit(x[i].imag()))
+                            is_about(r, -pi);
+                        else
+                            is_about(r, pi);
+                    }
+                    else
+                    {
+                        assert(r == 0);
+                        assert(std::signbit(r) == std::signbit(x[i].imag()));
+                    }
+                }
+                else
+                {
+                    if (x[i].imag() < 0)
+                        is_about(r, -pi/2);
+                    else
+                        is_about(r, pi/2);
+                }
+                break;
+            }
+        }
+    }
+}
+
+int main()
+{
+    test<float>();
+    test<double>();
+    test<long double>();
+    test_edges();
+}