Set up the test infrastructure

This is essentially copy-pasted from the cla-sysrepo private project.

Change-Id: Ie8c348536ab42481d79b060867f6c9f0443dba18
diff --git a/tests/trompeloeil_catch.h b/tests/trompeloeil_catch.h
new file mode 100644
index 0000000..c6d1131
--- /dev/null
+++ b/tests/trompeloeil_catch.h
@@ -0,0 +1,67 @@
+#pragma once
+
+#ifdef REQUIRE
+# error This file needs to be included prior to including anything from Catch.
+#endif
+
+// clang-format off
+
+#include <ostream>
+#include <thread>
+#include <catch.hpp>
+#include <trompeloeil.hpp>
+
+// this is copy-paste from https://github.com/rollbear/trompeloeil/blob/master/docs/CookBook.md/#unit_test_frameworks
+namespace trompeloeil {
+
+/** @short Pass reports from the Trompeloeil mocker to Catch for processing as test failures */
+template <>
+struct reporter<trompeloeil::specialized>
+{
+  static void send(trompeloeil::severity s,
+                   const char* file,
+                   unsigned long line,
+                   const char* msg)
+  {
+    std::ostringstream os;
+    if (line) os << file << ':' << line << '\n';
+    os << msg;
+    auto failure = os.str();
+    if (s == severity::fatal)
+    {
+      FAIL(failure);
+    }
+    else
+    {
+      CAPTURE(failure);
+      CHECK(failure.empty());
+    }
+  }
+};
+}
+
+/** @short Wait until a given sequence of expectation is matched, and then a bit more to ensure that there's silence afterwards */
+void waitForCompletionAndBitMore(const trompeloeil::sequence& seq)
+{
+    using namespace std::literals;
+    using clock = std::chrono::steady_clock;
+
+    // We're busy-waiting a bit
+    const auto waitingStep = 30ms;
+    // Timeout after this much
+    const auto completionTimeout = 5000ms;
+    // When checking for silence afterwards, wait at least this long.
+    // We'll also wait as long as it originally took to process everything.
+    const auto minExtraWait = 100ms;
+
+    auto start = clock::now();
+    while (!seq.is_completed()) {
+        std::this_thread::sleep_for(waitingStep);
+        if (clock::now() - start > completionTimeout) {
+            break;
+        }
+    }
+    REQUIRE(seq.is_completed());
+    auto duration = std::chrono::duration<double>(clock::now() - start);
+    std::this_thread::sleep_for(std::max(duration, decltype(duration)(minExtraWait)));
+}