Add unsetenv and also setenv macros and tests

tst/common/CommonDefsTest.cpp

@@ -11,3 +11,62 @@ TEST(CommonDefsTest, GetEnvWorks)
 {
     EXPECT_NE(nullptr, GETENV("PATH")) << "PATH environment variable is unexpectedly unset, or GETENV doesn't work";
 }
+
+
+// On Windows, getenv() doesn't work with SetEnvironmentVariable().
+// We'll need to use SetEnvironmentVariable() and GetEnvironmentVariable() together for runtime changes.
+// However, getenv does work in Windows (above test: GetEnvWorks) when the variable is set before program execution.
+// Note: SetEnvironmentVariable and GetEnvironmentVariable have different APIs to getenv and setenv.
+#ifndef __WINDOWS_BUILD__
+TEST(CommonDefsTest, SetEnvWorks)
+{
+    const char* test_var = "MY_TEST_VAR";
+    const char* test_value = "test_value";
+
+    // Save the original value of the environment variable, if it exists
+    const char* original_value = GETENV(test_var);
+
+    // Set the environment variable to a new value
+    setenv(test_var, test_value, 1);
+
+    // Verify if the environment variable was set correctly
+    EXPECT_STREQ(test_value, GETENV(test_var)) << "Failed to set environment variable " << test_var;
+
+    // Restore the original environment variable value (if any)
+    if (original_value) {
+        setenv(test_var, original_value, 1);
+    } else {
+        // If it was not set, unset the variable
+        unsetenv(test_var);
+    }
+}
+
+TEST(CommonDefsTest, UnsetEnvWorks)
+{
+    const char* test_var = "MY_TEST_VAR";
+    const char* test_value = "test_value";
+
+    // Save the original value of the environment variable, if it exists
+    const char* original_value = GETENV(test_var);
+
+    // Set the environment variable to a new value
+    setenv(test_var, test_value, 1);
+
+    // Verify if the environment variable was set correctly
+    EXPECT_STREQ(test_value, GETENV(test_var)) << "Failed to set environment variable " << test_var;
+
+    // Unset the environment variable
+    unsetenv(test_var);
+
+    // Verify if the environment variable is properly unset
+    EXPECT_EQ(nullptr, GETENV(test_var)) << "Failed to unset environment variable " << test_var;
+
+    // Restore the original environment variable value (if any)
+    if (original_value) {
+        setenv(test_var, original_value, 1);
+    } else {
+        // If it was not set, unset the variable
+        unsetenv(test_var);
+    }
+}
+#endif