Add test_double_quotes test

The new test ensures that no regressions are introduced in the future.

test/CMakeLists.txt

@@ -1,4 +1,4 @@
-set(test_names test_subprocess test_cat test_env test_err_redirection test_exception test_split test_main test_ret_code)
+set(test_names test_subprocess test_cat test_double_quotes test_env test_err_redirection test_exception test_split test_main test_ret_code)
 set(test_files env_script.sh write_err.sh write_err.txt)
 
 

test/test_double_quotes.cc

@@ -0,0 +1,30 @@
+#include <subprocess.hpp>
+
+#include <cassert>
+#include <string>
+
+namespace sp = subprocess;
+
+// JSON requires the use of double quotes (see: https://json.org/).
+// This test verifies proper handling of them.
+void test_double_quotes()
+{
+    // A simple JSON object.
+    const std::string expected{"{\"name\": \"value\"}"};
+#ifdef __USING_WINDOWS__
+    const std::string command{"cmd.exe /c echo "};
+#else
+    const std::string command{"echo "};
+#endif
+    auto p = sp::Popen(command + expected, sp::output{sp::PIPE});
+    const auto out = p.communicate().first;
+    std::string result{out.buf.begin(), out.buf.end()};
+    // The `echo` command appends a newline.
+    result.erase(result.find_last_not_of(" \n\r\t") + 1);
+    assert(result == expected);
+}
+
+int main() {
+  test_double_quotes();
+  return 0;
+}