Updated docs and wrote unit tests for lmp_set_fix_external_callback; fixed typos

unittest/fortran/wrap_fixexternal.cpp

@@ -0,0 +1,75 @@
+
+// unit tests for gathering and scattering data from a LAMMPS instance through
+// the Fortran wrapper
+
+#include "lammps.h"
+#include "library.h"
+#include <cstdint>
+#include <cstdlib>
+#include <mpi.h>
+#include <string>
+
+#include "gtest/gtest.h"
+
+// prototypes for Fortran reverse wrapper functions
+extern "C" {
+void *f_lammps_with_args();
+void f_lammps_close();
+void f_lammps_setup_fix_external();
+void f_lammps_set_fix_external_callbacks();
+void f_lammps_get_force(int, double*);
+void f_lammps_reverse_direction();
+}
+
+using namespace LAMMPS_NS;
+
+class LAMMPS_fixexternal : public ::testing::Test {
+protected:
+    LAMMPS_NS::LAMMPS *lmp;
+    LAMMPS_fixexternal()           = default;
+    ~LAMMPS_fixexternal() override = default;
+
+    void SetUp() override
+    {
+        ::testing::internal::CaptureStdout();
+        lmp                = (LAMMPS_NS::LAMMPS *)f_lammps_with_args();
+        std::string output = ::testing::internal::GetCapturedStdout();
+        EXPECT_STREQ(output.substr(0, 8).c_str(), "LAMMPS (");
+    }
+    void TearDown() override
+    {
+        ::testing::internal::CaptureStdout();
+        f_lammps_close();
+        std::string output = ::testing::internal::GetCapturedStdout();
+        EXPECT_STREQ(output.substr(0, 16).c_str(), "Total wall time:");
+        lmp = nullptr;
+    }
+};
+
+TEST_F(LAMMPS_fixexternal, callback)
+{
+    f_lammps_setup_fix_external();
+    f_lammps_set_fix_external_callbacks();
+    lammps_command(lmp, "run 0");
+    double f[3];
+    f_lammps_get_force(1,f);
+    EXPECT_DOUBLE_EQ(f[0], 3.0);
+    EXPECT_DOUBLE_EQ(f[1], -3.0);
+    EXPECT_DOUBLE_EQ(f[2], 3.75);
+    f_lammps_get_force(2,f);
+    EXPECT_DOUBLE_EQ(f[0], -3.0);
+    EXPECT_DOUBLE_EQ(f[1], 3.0);
+    EXPECT_DOUBLE_EQ(f[2], -3.75);
+
+    f_lammps_reverse_direction();
+    f_lammps_set_fix_external_callbacks();
+    lammps_command(lmp, "run 0");
+    f_lammps_get_force(1,f);
+    EXPECT_DOUBLE_EQ(f[0], -1.0);
+    EXPECT_DOUBLE_EQ(f[1], 1.0);
+    EXPECT_DOUBLE_EQ(f[2], -1.25);
+    f_lammps_get_force(2,f);
+    EXPECT_DOUBLE_EQ(f[0], 1.0);
+    EXPECT_DOUBLE_EQ(f[1], -1.0);
+    EXPECT_DOUBLE_EQ(f[2], 1.25);
+};