Functional tests for string module.

    Some of the tests do not pass, as there are bugs in the
    implementation of string functions.

src/tests/CMakeLists.txt

@@ -17,3 +17,10 @@ INCLUDE_DIRECTORIES (${dirlist})
 
 # All the generated files
 INCLUDE_DIRECTORIES (${PROJECT_BINARY_DIR}/src/libsac2c)
+
+# Generated global files like config, fun-attrs, etc.
+INCLUDE_DIRECTORIES (${PROJECT_BINARY_DIR}/src/include)
+
+ADD_EXECUTABLE (string-tests string-tests.cpp)
+TARGET_LINK_LIBRARIES (string-tests GTest::GTest GTest::Main sac2cShared)
+GTEST_ADD_TESTS(string-tests "" AUTO)  # maket it a part of ctest call

src/tests/string-tests.cpp

+#include <sys/types.h>
+#include <dirent.h>
+#include "gtest/gtest.h"
+
+extern "C" {
+#include "memory.h"
+#include "str.h"
+}
+
+TEST (StringOperations, testToUpper)
+{
+    char *t = strdup ("test");
+    STRtoupper (t, 0, 1);
+    EXPECT_STREQ ("Test", t);
+
+    STRtoupper (t, 0, 2);
+    EXPECT_STREQ ("TEst", t);
+
+    MEMfree (t);
+}
+
+// The code is total shite, it overruns the buffer
+TEST (StringOperations, testToUpperDoNotSegfault)
+{
+    char *t = strdup ("test");
+    EXPECT_NO_THROW (STRtoupper (t, 0, 1000000));
+    EXPECT_STREQ ("TEST", t);
+    MEMfree (t);
+}
+
+TEST (StringOperations, testStrCpy)
+{
+    char *t = STRcpy ("test");
+    EXPECT_STREQ ("test", t);
+    MEMfree (t);
+
+    char *tt = STRcpy (NULL);
+    EXPECT_EQ (tt, (void *)NULL);
+}
+
+
+TEST (StringOperations, testStrNCpy)
+{
+    char *t = STRncpy ("test", 2);
+    EXPECT_STREQ ("te", t);
+    MEMfree (t);
+}
+
+// This code is shite too, as it declares the size as int and doesn't check
+// for negative sizes.
+TEST (StringOperations, testStrNCpyDie)
+{
+    ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+    char *tt;
+    ASSERT_DEATH (tt = STRncpy ("test", -1), "Assertion");
+}
+
+// Again, what the hell we are supposed to do with negative lengths?
+TEST (StringOperations, testSubStr01)
+{
+    char *t = STRsubStr ("test01", -1, 1);
+    EXPECT_STREQ ("1", t);
+    MEMfree (t);
+}
+
+
+TEST (StringOperations, testSubStr02)
+{
+    char *t = STRsubStr ("test01", -10000, 1);
+    EXPECT_STREQ ("t", t);
+    MEMfree (t);
+}
+
+TEST (StringOperations, testSubStr03)
+{
+    char *t = STRsubStr ("test01", 1, 1);
+    EXPECT_STREQ ("e", t);
+    MEMfree (t);
+}
+
+TEST (StringOperations, testSubStr04)
+{
+    char *t = STRsubStr ("test01", 100, 1);
+    EXPECT_STREQ ("", t);
+    MEMfree (t);
+}
+
+TEST (StringOperations, testSubStr05)
+{
+    char *t = STRsubStr ("test01", 2, -100);
+    EXPECT_STREQ ("", t);
+    MEMfree (t);
+}
+