modules/kvs: Add corner case unit test

Add unit test when user passes in an invalid commit to commit_process().

src/modules/kvs/test/commit.c

@@ -745,6 +745,42 @@ void commit_basic_commit_process_test_multiple_fences_merge (void)
     cache_destroy (cache);
 }
 
+void commit_basic_commit_process_test_invalid_commit (void)
+{
+    struct cache *cache;
+    commit_mgr_t *cm;
+    commit_t *cbad, *c;
+    blobref_t rootref;
+
+    cache = create_cache_with_empty_rootdir (rootref);
+
+    ok ((cm = commit_mgr_create (cache,
+                                 KVS_PRIMARY_NAMESPACE,
+                                 "sha1",
+                                 NULL,
+                                 &test_global)) != NULL,
+        "commit_mgr_create works");
+
+    create_ready_commit (cm, "fence1", "key1", "1", 0, 0);
+    create_ready_commit (cm, "fence2", "key2", "2", 0, 0);
+
+    ok ((cbad = commit_mgr_get_ready_commit (cm)) != NULL,
+        "commit_mgr_get_ready_commit returns ready commit");
+
+    ok (commit_mgr_merge_ready_commits (cm) == 0,
+        "commit_mgr_merge_ready_commits success");
+
+    ok ((c = commit_mgr_get_ready_commit (cm)) != NULL,
+        "commit_mgr_get_ready_commit returns ready commit");
+
+    ok (commit_process (cbad, 1, rootref) == COMMIT_PROCESS_ERROR
+        && commit_get_errnum (cbad) == EINVAL,
+        "commit_process fails on bad commit");
+
+    commit_mgr_destroy (cm);
+    cache_destroy (cache);
+}
+
 void commit_basic_root_not_dir (void)
 {
     struct cache *cache;
@@ -2304,6 +2340,7 @@ int main (int argc, char *argv[])
     commit_basic_commit_process_test ();
     commit_basic_commit_process_test_multiple_fences ();
     commit_basic_commit_process_test_multiple_fences_merge ();
+    commit_basic_commit_process_test_invalid_commit ();
     commit_basic_root_not_dir ();
     commit_basic_iter_not_ready_tests ();
     commit_process_root_missing ();