add regression testing tasks (#664)

src/integration-tests/libfuzzer-regression/Makefile

@@ -0,0 +1,16 @@
+CC=clang
+
+CFLAGS=-g3 -fsanitize=fuzzer -fsanitize=address
+
+all: broken.exe fixed.exe
+
+broken.exe: simple.c
+	$(CC) $(CFLAGS) simple.c -o broken.exe
+
+fixed.exe: simple.c
+	$(CC) $(CFLAGS) simple.c -o fixed.exe -DFIXED
+
+.PHONY: clean
+
+clean:
+	rm -f broken.exe fixed.exe

src/integration-tests/libfuzzer-regression/seeds/good.txt

@@ -0,0 +1 @@
+good

src/integration-tests/libfuzzer-regression/simple.c

@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#include <stdint.h>
+#include <stdlib.h>
+
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t len) {
+  int cnt = 0;
+
+  if (len < 3) {
+    return 0;
+  }
+
+  if (data[0] == 'x') { cnt++; }
+  if (data[1] == 'y') { cnt++; }
+  if (data[2] == 'z') { cnt++; }
+
+#ifndef FIXED
+  if (cnt >= 3) {
+     abort();
+  }
+#endif
+
+  return 0;
+}