Added the hook for checking programmer error responses, and made sure it works. Now to simplify it.

common/errors.c

@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include "ui.h"
 #include "uipriv.h"
+#include "testhooks.h"
 
 #define internalErrorPrefix "libui internal error"
 // TODO add debugging advice?
@@ -53,6 +54,15 @@ static void prepareProgrammerError(char *buf, int size, unsigned int which, va_l
 // TODO add debugging advice?
 #define programmerErrorSuffix "This likely means you are using libui incorrectly. Check your source code and try again. If you have received this warning in error, contact the libui authors."
 
+static uiprivTestHookReportProgrammerErrorFunc reportProgrammerErrorTestHook = uiprivReportError;
+
+void uiprivTestHookReportProgrammerError(uiprivTestHookReportProgrammerErrorFunc f)
+{
+	if (f == NULL)
+		f = uiprivReportError;
+	reportProgrammerErrorTestHook = f;
+}
+
 void uiprivProgrammerError(unsigned int which, ...)
 {
 	va_list ap;
@@ -61,5 +71,5 @@ void uiprivProgrammerError(unsigned int which, ...)
 	va_start(ap, which);
 	prepareProgrammerError(buf, 256, which, ap);
 	va_end(ap);
-	uiprivReportError(programmerErrorPrefix, buf, programmerErrorSuffix, false);
+	(*reportProgrammerErrorTestHook)(programmerErrorPrefix, buf, programmerErrorSuffix, false);
 }

common/testhooks.h

@@ -0,0 +1,13 @@
+// 26 may 2019
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// errors.c
+typedef void (*uiprivTestHookReportProgrammerErrorFunc)(const char *prefix, const char *msg, const char *suffix, bool internal);
+uiprivExtern void uiprivTestHookReportProgrammerError(uiprivTestHookReportProgrammerErrorFunc f);
+
+#ifdef __cplusplus
+}
+#endif

test/events.c

@@ -684,7 +684,36 @@ testingTest(EventBlocksHonoredWithDifferentSenders)
 	runGlobalSubtests(t, &p);
 }
 
+static struct {
+	testingT *t;
+	const char *msgWant;
+	bool caught;
+} errorParams;
+
+static void catchProgrammerError(const char *prefix, const char *msg, const char *suffix, bool internal)
+{
+	errorParams.caught = true;
+	if (strstr(prefix, "programmer error") == NULL)
+		testingTErrorf(errorParams.t, "prefix string doesn't contain \"programmer error\": %s", prefix);
+	if (internal)
+		testingTErrorf(errorParams.t, "error is marked internal; should not have been");
+	if (strstr(msg, errorParams.msgWant) == NULL)
+		diff(errorParams.t, "message doesn't contain expected substring",
+			"%s", msg, errorParams.msgWant);
+}
+
 testingTest(EventErrors)
 {
-	// TODO
+	uiprivTestHookReportProgrammerError(catchProgrammerError);
+
+	testingTLogf(t, "*** uiNewEvent(NULL)");
+	errorParams.t = t;
+	errorParams.msgWant = "invalid null pointer for uiEventOptions passed into uiNewEvent()";
+	errorParams.caught = false;
+	if (uiNewEvent(NULL) != NULL)
+		testingTErrorf(t, "uiNewEvent(NULL) returned non-NULL; wanted NULL");
+	if (!errorParams.caught)
+		testingTErrorf(t, "uiNewEvent(NULL) did not throw a programmer error; should have");
+
+	uiprivTestHookReportProgrammerError(NULL);
 }

test/test.h

@@ -1,5 +1,6 @@
 // 28 april 2019
 #include "../ui.h"
+#include "../common/testhooks.h"
 #include "lib/testing.h"
 #include "lib/timer.h"