1 files changed, 45 insertions, 0 deletions
diff --git a/tests/io_tester.hpp b/tests/io_tester.hpp
new file mode 100644
index 0000000..b9cdaa7
--- /dev/null
+++ b/tests/io_tester.hpp
@@ -0,0 +1,45 @@
+#pragma once
+
+#include <ostream>
+#include <sstream>
+
+/**
+ * Redirects a stream into a streambuf until the object is destroyed.
+ */
+template <typename StreamType>
+class IoTester
+{
+public:
+  IoTester(StreamType& ios):
+    stream{},
+    ios(ios),
+    old_buf(ios.rdbuf())
+  {
+    // Redirect the given os into our stringstream’s buf
+    this->ios.rdbuf(this->stream.rdbuf());
+  }
+  ~IoTester()
+  {
+    this->ios.rdbuf(this->old_buf);
+  }
+  IoTester& operator=(const IoTester&) = delete;
+  IoTester& operator=(IoTester&&) = delete;
+  IoTester(const IoTester&) = delete;
+  IoTester(IoTester&&) = delete;
+
+  std::string str() const
+  {
+    return this->stream.str();
+  }
+
+  void set_string(const std::string& s)
+  {
+    this->stream.str(s);
+  }
+
+private:
+  std::stringstream stream;
+  StreamType& ios;
+  std::streambuf* const old_buf;
+};
+