From 7cf20ef70aef9c80b00e3e2c80d9e025054baae2 Mon Sep 17 00:00:00 2001
From: Ethan Frey <ethanfrey@users.noreply.github.com>
Date: Thu, 3 Aug 2017 16:58:57 +0200
Subject: [PATCH] Add test to enforce deteministic application of cache order

---
 state/merkle_test.go | 100 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 state/merkle_test.go

diff --git a/state/merkle_test.go b/state/merkle_test.go
new file mode 100644
index 000000000000..d6c9f577b955
--- /dev/null
+++ b/state/merkle_test.go
@@ -0,0 +1,100 @@
+package state
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/tendermint/merkleeyes/iavl"
+)
+
+type keyVal struct {
+	key string
+	val string
+}
+
+func (kv keyVal) getKV() ([]byte, []byte) {
+	return []byte(kv.key), []byte(kv.val)
+}
+
+type round []keyVal
+
+// make sure the commits are deterministic
+func TestStateCommitHash(t *testing.T) {
+	assert, require := assert.New(t), require.New(t)
+
+	cases := [...]struct {
+		rounds []round
+	}{
+		// simple, two rounds, no overlap
+		0: {
+			[]round{
+				[]keyVal{{"abc", "123"}, {"def", "456"}},
+				[]keyVal{{"more", "news"}, {"good", "news"}},
+			},
+		},
+		// more complex, order should change if applyCache is not deterministic
+		1: {
+			[]round{
+				[]keyVal{{"abc", "123"}, {"def", "456"}, {"foo", "789"}, {"dings", "646"}},
+				[]keyVal{{"hf", "123"}, {"giug", "456"}, {"kgiuvgi", "789"}, {"kjguvgk", "646"}},
+				[]keyVal{{"one", "more"}, {"two", "things"}, {"uh", "oh"}, {"a", "2"}},
+			},
+		},
+		// make sure ordering works with overwriting as well
+		2: {
+			[]round{
+				[]keyVal{{"abc", "123"}, {"def", "456"}, {"foo", "789"}, {"dings", "646"}},
+				[]keyVal{{"hf", "123"}, {"giug", "456"}, {"kgiuvgi", "789"}, {"kjguvgk", "646"}},
+				[]keyVal{{"abc", "qqq"}, {"def", "www"}, {"foo", "ee"}, {"dings", "ff"}},
+				[]keyVal{{"one", "more"}, {"uh", "oh"}, {"a", "2"}},
+				[]keyVal{{"hf", "dd"}, {"giug", "gg"}, {"kgiuvgi", "jj"}, {"kjguvgk", "uu"}},
+			},
+		},
+	}
+
+	for i, tc := range cases {
+		// let's run all rounds... they must each be different,
+		// and they must have the same results each run
+		var hashes [][]byte
+
+		// try each 5 times for deterministic check
+		for j := 0; j < 5; j++ {
+			result := make([][]byte, len(tc.rounds))
+
+			// make the store...
+			tree := iavl.NewIAVLTree(0, nil)
+			store := NewState(tree, false)
+
+			for n, r := range tc.rounds {
+				// start the cache
+				deliver := store.Append()
+				for _, kv := range r {
+					// add the value to cache
+					k, v := kv.getKV()
+					deliver.Set(k, v)
+				}
+				// commit and add hash to result
+				hash, err := store.Commit()
+				require.Nil(err, "tc:%d / rnd:%d - %+v", i, n, err)
+				result[n] = hash
+			}
+
+			// make sure result is all unique
+			for n := 0; n < len(result)-1; n++ {
+				assert.NotEqual(result[n], result[n+1], "tc:%d / rnd:%d", i, n)
+			}
+
+			// if hashes != nil, make sure same as last trial
+			if hashes != nil {
+				for n := 0; n < len(result); n++ {
+					assert.Equal(hashes[n], result[n], "tc:%d / rnd:%d", i, n)
+				}
+			}
+			// store to check against next trial
+			hashes = result
+		}
+	}
+
+}