Add kill-waitpid test.

tests/kill-waitpid.c

@@ -0,0 +1,36 @@
+#include <assert.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/wait.h>
+
+#include "test_helpers.h"
+
+int main(void) {
+    int err;
+
+    int fds[2];
+    err = pipe(fds);
+    ERROR_IF(pipe, err, == -1);
+
+    int child = fork();
+    ERROR_IF(fork, child, == -1);
+
+    if (child == 0) {
+        // block forever
+        char buf[1];
+        read(fds[0], buf, 1);
+    }
+
+    err = kill(child, SIGTERM);
+    ERROR_IF(kill, err, == -1);
+
+    int status;
+    err = waitpid(child, &status, 0);
+    ERROR_IF(waitpid, err, == -1);
+    printf("STATUS %d\n", status);
+    assert(WIFSIGNALED(status));
+    assert(WTERMSIG(status) == SIGTERM);
+}