catch_discover_tests uses tempfile to retrieve JSON from the binary

This allows it to deal with badly behaved code, where 3rd party
dependencies write into stdout during global construction.

Closes #3162
Closes #3166

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/TestScripts/DiscoverTests/register-tests.cpp b/tests/TestScripts/DiscoverTests/register-tests.cpp
index be533ab6..8b071196 100644
--- a/tests/TestScripts/DiscoverTests/register-tests.cpp
+++ b/tests/TestScripts/DiscoverTests/register-tests.cpp
@@ -8,6 +8,24 @@
 
 #include <catch2/catch_test_macros.hpp>
 
+#include <cstdio>
+#include <iostream>
+
+namespace {
+
+struct PrintsWhenConstructed {
+    PrintsWhenConstructed() {
+        std::cout << "Hello\n";
+        std::cerr << "Holla\n";
+        std::fprintf(stdout, "Hullo\n");
+        std::fprintf(stderr, "Hillo\n");
+    }
+};
+
+static PrintsWhenConstructed instance;
+
+}
+
 TEST_CASE("@Script[C:\\EPM1A]=x;\"SCALA_ZERO:\"", "[script regressions]"){}
 TEST_CASE("Some test") {}
 TEST_CASE( "Let's have a test case with a long name. Longer. No, even longer. "