Reintegrated what I needed in test.h. So much for "overengineered".

test/main.c

@@ -36,6 +36,30 @@ static int testcmp(const void *aa, const void *bb)
 	return strcmp(a->name, b->name);
 }
 
+static const char *basename(const char *file)
+{
+	const char *p;
+
+	for (;;) {
+		p = strpbrk(file, "/\\");
+		if (p == NULL)
+			break;
+		file = p + 1;
+	}
+	return file;
+}
+
+void testingprivLogf(FILE *f, const char *filename, long line, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fprintf(f, "%s:%ld: ", basename(filename), line);
+	vfprintf(f, fmt, ap);
+	fprintf(f, "\n");
+	va_end(ap);
+}
+
 int main(int argc, char *argv[])
 {
 	struct test *t;

test/test.h

@@ -17,6 +17,10 @@ extern "C" {
 
 #define testingprivImplName(basename) testingprivImpl ## basename
 
+#define testingprivScaffoldName(basename) testingprivScaffold ## basename
+#define testingprivMkScaffold(basename) \
+	static int testingprivScaffoldName(basename)(void) { int ret = 0; testingprivImplName(basename)(&ret); return ret; }
+
 // references:
 // - https://gitlab.gnome.org/GNOME/glib/blob/master/glib/gconstructor.h
 // - https://gitlab.gnome.org/GNOME/glib/blob/master/gio/glib-compile-resources.c
@@ -25,35 +29,52 @@ extern "C" {
 #define testingprivCtorPtrName(basename) testingprivCtorPtr ## basename
 #if defined(__GNUC__)
 #define testingprivMkCtor(basename) \
-	__attribute__((constructor)) static void testingprivCtorName(basename)(void) { testingprivRegisterTest(#basename, testingprivImplName(basename)); }
+	__attribute__((constructor)) static void testingprivCtorName(basename)(void) { testingprivRegisterTest(#basename, testingprivScaffoldName(basename)); }
 #elif defined(_MSC_VER)
 #define testingprivMkCtor(basename) \
-	static int testingprivCtorName(basename)(void) { testingprivRegisterTest(#basename, testingprivImplName(basename)); return 0; } \
+	static int testingprivCtorName(basename)(void) { testingprivRegisterTest(#basename, testingprivScaffoldName(basename)); return 0; } \
 	__pragma(section(".CRT$XCU",read)) \
 	__declspec(allocate(".CRT$XCU")) static int (*testingprivCtorPtrName(basename))(void) = testingprivCtorName(basename);
 #elif defined(__SUNPRO_C)
 #define testingprivMkCtor(basename) \
-	static void testingprivCtorName(basename)(void) { testingprivRegisterTest(#basename, testingprivImplName(basename)); } \
+	static void testingprivCtorName(basename)(void) { testingprivRegisterTest(#basename, testingprivScaffoldName(basename)); } \
 	_Pragma(init(testingprivCtorName(basename)))
 #else
 #error unknown compiler for making constructors in C; cannot continue
 #endif
 
 #define Test(basename) \
-	int testingprivImplName(basename)(void); \
+	void testingprivImplName(basename)(int *testingprivRet); \
+	testingprivMkScaffold(basename) \
 	testingprivMkCtor(basename) \
-	int testingprivImplName(basename)(void)
+	void testingprivImplName(basename)(int *testingprivRet)
 
 #define Test(Name) \
 	testingprivMk(Test ## Name)
 
 // These can only be called directly from the Test functions.
 // TODO make it otherwise
-#define TestFailNow() return 1
+#define TestFail() (*testingprivRet = 1)
+#define TestFailNow() {TestFail(); return;}
 // see https://mesonbuild.com/Unit-tests.html#skipped-tests-and-hard-errors
-#define TestSkipNow() return 77
+#define TestSkipNow() {*testingprivRet = 77; return;}
+
+#define TestLogf(...) \
+	(testingprivLogf(stdout, __FILE__, __LINE__, __VA_ARGS__))
+#define TestErrorf(...) \
+	{testingprivLogf(stderr, __FILE__, __LINE__, __VA_ARGS__); TestFail();}
+#define TestFatalf(...) \
+	{testingprivLogf(stderr, __FILE__, __LINE__, __VA_ARGS__); TestFailNow();}
+// TODO remember if this needs to go to stdout or to stderr
+#define TestSkipf(...) \
+	{testingprivLogf(stderr, __FILE__, __LINE__, __VA_ARGS__); TestSkipNow();}
 
 extern void testingprivRegisterTest(const char *name, int (*f)(void));
+#include "../sharedbits/printfwarn_header.h"
+sharedbitsPrintfFunc(
+	extern void testingprivLogf(FILE *f, const char *filename, long line, const char *fmt, ...),
+	4, 5);
+#undef sharedbitsPrintfFunc
 
 #ifdef __cplusplus
 }