Renamed a few things and converted the examples to proper tests

extension_node.go

@@ -132,11 +132,11 @@ func (extNode *extensionNode) split(path []byte) (trieNode, *trieNode, int) {
 
 // expand returns the inner node that represents the start of the singly
 // linked list that this extension node represents
-func (ext *extensionNode) expand() trieNode {
-	last := ext.child
-	for i := ext.pathEnd() - 1; i >= ext.pathStart(); i-- {
+func (extNode *extensionNode) expand() trieNode {
+	last := extNode.child
+	for i := extNode.pathEnd() - 1; i >= extNode.pathStart(); i-- {
 		var next innerNode
-		if getPathBit(ext.path, i) == leftChildBit {
+		if getPathBit(extNode.path, i) == leftChildBit {
 			next.leftChild = last
 		} else {
 			next.rightChild = last

proofs.go

@@ -283,7 +283,7 @@ func VerifyProof(proof *SparseMerkleProof, root, key, value []byte, spec *TrieSp
 func VerifySumProof(proof *SparseMerkleProof, root, key, value []byte, sum uint64, spec *TrieSpec) (bool, error) {
 	var sumBz [sumSizeBits]byte
 	binary.BigEndian.PutUint64(sumBz[:], sum)
-	valueHash := spec.digestValue(value)
+	valueHash := spec.valueDigest(value)
 	valueHash = append(valueHash, sumBz[:]...)
 	if bytes.Equal(value, defaultEmptyValue) && sum == 0 {
 		valueHash = defaultEmptyValue
@@ -348,7 +348,7 @@ func verifyProofWithUpdates(proof *SparseMerkleProof, root []byte, key []byte, v
 			updates = append(updates, update)
 		}
 	} else { // Membership proof.
-		valueHash := spec.digestValue(value)
+		valueHash := spec.valueDigest(value)
 		currentHash, currentData = digestLeaf(spec, path, valueHash)
 		update := make([][]byte, 2)
 		update[0], update[1] = currentHash, currentData

smst.go

@@ -84,7 +84,7 @@ func (smst *SMST) Get(key []byte) ([]byte, uint64, error) {
 // appended with the binary representation of the weight provided. The weight
 // is used to compute the interim and total sum of the trie.
 func (smst *SMST) Update(key, value []byte, weight uint64) error {
-	valueHash := smst.digestValue(value)
+	valueHash := smst.valueDigest(value)
 	var weightBz [sumSizeBits]byte
 	binary.BigEndian.PutUint64(weightBz[:], weight)
 	valueHash = append(valueHash, weightBz[:]...)

smst_example_test.go

@@ -2,18 +2,21 @@ package smt_test
 
 import (
 	"crypto/sha256"
-	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
 
 	"github.com/pokt-network/smt"
 	"github.com/pokt-network/smt/kvstore/simplemap"
 )
 
-func ExampleSMST() {
-	// Initialise a new in-memory key-value store to store the nodes of the trie
+// TestExampleSMT is a test that aims to act as an example of how to use the SMST.
+func TestExampleSMST(t *testing.T) {
+	// Initialize a new in-memory key-value store to store the nodes of the trie
 	// (Note: the trie only stores hashed values, not raw value data)
 	nodeStore := simplemap.NewSimpleMap()
 
-	// Initialise the trie
+	// Initialize the trie
 	trie := smt.NewSparseMerkleSumTrie(nodeStore, sha256.New())
 
 	// Update trie with keys, values and their sums
@@ -36,13 +39,25 @@ func ExampleSMST() {
 	root := trie.Root()
 
 	// Verify the Merkle proof for "foo"="oof" where "foo" has a sum of 10
-	valid_true1, _ := smt.VerifySumProof(proof1, root, []byte("foo"), []byte("oof"), 10, trie.Spec())
+	valid_true1, err := smt.VerifySumProof(proof1, root, []byte("foo"), []byte("oof"), 10, trie.Spec())
+	require.NoError(t, err)
+	require.True(t, valid_true1)
+
 	// Verify the Merkle proof for "baz"="zab" where "baz" has a sum of 7
-	valid_true2, _ := smt.VerifySumProof(proof2, root, []byte("baz"), []byte("zab"), 7, trie.Spec())
+	valid_true2, err := smt.VerifySumProof(proof2, root, []byte("baz"), []byte("zab"), 7, trie.Spec())
+	require.NoError(t, err)
+	require.True(t, valid_true2)
+
 	// Verify the Merkle proof for "bin"="nib" where "bin" has a sum of 3
-	valid_true3, _ := smt.VerifySumProof(proof3, root, []byte("bin"), []byte("nib"), 3, trie.Spec())
+	valid_true3, err := smt.VerifySumProof(proof3, root, []byte("bin"), []byte("nib"), 3, trie.Spec())
+	require.NoError(t, err)
+	require.True(t, valid_true3)
+
 	// Fail to verify the Merkle proof for "foo"="oof" where "foo" has a sum of 11
-	valid_false1, _ := smt.VerifySumProof(proof1, root, []byte("foo"), []byte("oof"), 11, trie.Spec())
-	fmt.Println(valid_true1, valid_true2, valid_true3, valid_false1)
+	valid_false1, err := smt.VerifySumProof(proof1, root, []byte("foo"), []byte("oof"), 11, trie.Spec())
+	require.NoError(t, err)
+	require.False(t, valid_false1)
+
 	// Output: true true true false
+	t.Log(valid_true1, valid_true2, valid_true3, valid_false1)
 }

smst_proofs_test.go

@@ -105,7 +105,7 @@ func TestSMST_Proof_Operations(t *testing.T) {
 	// Try proving a default value for a non-default leaf.
 	var sum [sumSizeBits]byte
 	binary.BigEndian.PutUint64(sum[:], 5)
-	tval := base.digestValue([]byte("testValue"))
+	tval := base.valueDigest([]byte("testValue"))
 	tval = append(tval, sum[:]...)
 	_, leafData := base.th.digestSumLeaf(base.ph.Path([]byte("testKey2")), tval)
 	proof = &SparseMerkleProof{

smst_utils_test.go

@@ -26,7 +26,7 @@ func (smst *SMSTWithStorage) Update(key, value []byte, sum uint64) error {
 	if err := smst.SMST.Update(key, value, sum); err != nil {
 		return err
 	}
-	valueHash := smst.digestValue(value)
+	valueHash := smst.valueDigest(value)
 	var sumBz [sumSizeBits]byte
 	binary.BigEndian.PutUint64(sumBz[:], sum)
 	value = append(value, sumBz[:]...)

smt.go

@@ -108,7 +108,7 @@ func (smt *SMT) Get(key []byte) ([]byte, error) {
 func (smt *SMT) Update(key []byte, value []byte) error {
 	// Expand
 	path := smt.ph.Path(key)
-	valueHash := smt.digestValue(value)
+	valueHash := smt.valueDigest(value)
 	var orphans orphanNodes
 	trie, err := smt.update(smt.root, 0, path, valueHash, &orphans)
 	if err != nil {

smt_example_test.go

@@ -2,18 +2,19 @@ package smt_test
 
 import (
 	"crypto/sha256"
-	"fmt"
+	"testing"
 
 	"github.com/pokt-network/smt"
 	"github.com/pokt-network/smt/kvstore/simplemap"
 )
 
-func ExampleSMT() {
-	// Initialise a new in-memory key-value store to store the nodes of the trie
+// TestExampleSMT is a test that aims to act as an example of how to use the SMST.
+func TestExampleSMT(t *testing.T) {
+	// Initialize a new in-memory key-value store to store the nodes of the trie
 	// (Note: the trie only stores hashed values, not raw value data)
 	nodeStore := simplemap.NewSimpleMap()
 
-	// Initialise the trie
+	// Initialize the trie
 	trie := smt.NewSparseMerkleTrie(nodeStore, sha256.New())
 
 	// Update the key "foo" with the value "bar"
@@ -30,6 +31,7 @@ func ExampleSMT() {
 	valid, _ := smt.VerifyProof(proof, root, []byte("foo"), []byte("bar"), trie.Spec())
 	// Attempt to verify the Merkle proof for "foo"="baz"
 	invalid, _ := smt.VerifyProof(proof, root, []byte("foo"), []byte("baz"), trie.Spec())
-	fmt.Println(valid, invalid)
+
 	// Output: true false
+	t.Log(valid, invalid)
 }

smt_proofs_test.go

@@ -84,7 +84,7 @@ func TestSMT_Proof_Operations(t *testing.T) {
 	require.False(t, result)
 
 	// Try proving a default value for a non-default leaf.
-	_, leafData := base.th.digestLeaf(base.ph.Path([]byte("testKey2")), base.digestValue([]byte("testValue")))
+	_, leafData := base.th.digestLeaf(base.ph.Path([]byte("testKey2")), base.valueDigest([]byte("testValue")))
 	proof = &SparseMerkleProof{
 		SideNodes:             proof.SideNodes,
 		NonMembershipLeafData: leafData,

smt_utils_test.go

@@ -24,7 +24,7 @@ func (smt *SMTWithStorage) Update(key, value []byte) error {
 	if err := smt.SMT.Update(key, value); err != nil {
 		return err
 	}
-	valueHash := smt.digestValue(value)
+	valueHash := smt.valueDigest(value)
 	return smt.preimages.Set(valueHash, value)
 }
 

types.go

@@ -108,35 +108,39 @@ func (spec *TrieSpec) Spec() *TrieSpec {
 
 // depth returns the maximum depth of the trie.
 // Since this tree is a binary tree, the depth is the number of bits in the path
+// TODO_IN_THIS_PR: Try to understand why we're not taking the log of the output
 func (spec *TrieSpec) depth() int {
 	return spec.ph.PathSize() * 8 // path size is in bytes so multiply by 8 to get num bits
 }
 
-func (spec *TrieSpec) digestValue(data []byte) []byte {
+// valueDigest returns the hash of a value, or the value itself if no value hasher is specified.
+func (spec *TrieSpec) valueDigest(value []byte) []byte {
 	if spec.vh == nil {
-		return data
+		return value
 	}
-	return spec.vh.HashValue(data)
+	return spec.vh.HashValue(value)
 }
 
-func (spec *TrieSpec) serialize(node trieNode) (data []byte) {
+// encodeNode serializes a node into a byte slice
+func (spec *TrieSpec) encodeNode(node trieNode) (data []byte) {
 	switch n := node.(type) {
 	case *lazyNode:
-		panic("serialize(lazyNode)")
+		panic("Encoding a lazyNode is not supported")
 	case *leafNode:
 		return encodeLeafNode(n.path, n.valueHash)
 	case *innerNode:
-		lchild := spec.hashNode(n.leftChild)
-		rchild := spec.hashNode(n.rightChild)
-		return encodeInnerNode(lchild, rchild)
+		leftChild := spec.digestNode(n.leftChild)
+		rightChild := spec.digestNode(n.rightChild)
+		return encodeInnerNode(leftChild, rightChild)
 	case *extensionNode:
-		child := spec.hashNode(n.child)
+		child := spec.digestNode(n.child)
 		return encodeExtensionNode(n.pathBounds, n.path, child)
 	}
 	return nil
 }
 
-func (spec *TrieSpec) hashNode(node trieNode) []byte {
+// digestNode hashes a node returning its digest
+func (spec *TrieSpec) digestNode(node trieNode) []byte {
 	if node == nil {
 		return spec.th.placeholder()
 	}
@@ -150,12 +154,12 @@ func (spec *TrieSpec) hashNode(node trieNode) []byte {
 		cache = &n.digest
 	case *extensionNode:
 		if n.digest == nil {
-			n.digest = spec.hashNode(n.expand())
+			n.digest = spec.digestNode(n.expand())
 		}
 		return n.digest
 	}
 	if *cache == nil {
-		*cache = spec.th.digest(spec.serialize(node))
+		*cache = spec.th.digest(spec.encodeNode(node))
 	}
 	return *cache
 }

utils.go

@@ -157,15 +157,15 @@ func hashNode(spec *TrieSpec, node trieNode) []byte {
 	if spec.sumTrie {
 		return spec.hashSumNode(node)
 	}
-	return spec.hashNode(node)
+	return spec.digestNode(node)
 }
 
 // serialize serializes a node depending on the trie type
 func serialize(spec *TrieSpec, node trieNode) []byte {
 	if spec.sumTrie {
 		return spec.sumSerialize(node)
 	}
-	return spec.serialize(node)
+	return spec.encodeNode(node)
 }
 
 // hashPreimage hashes the serialised data provided depending on the trie type
@@ -182,7 +182,7 @@ func hashSerialization(smt *TrieSpec, data []byte) []byte {
 		pathBounds, path, childHash := parseExtension(data, smt.ph)
 		ext := extensionNode{path: path, child: &lazyNode{childHash}}
 		copy(ext.pathBounds[:], pathBounds)
-		return smt.hashNode(&ext)
+		return smt.digestNode(&ext)
 	}
 	return smt.th.digest(data)
 }