fix cassandra driver: always provide state hash (#28)

* always provide state hash

* fix unit tests

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+## [v0.5.2]
+- Always provide a state hash cassandra  [#28](https://github.com/xmidt-org/codex-db/pull/28)
+
 ## [v0.5.1]
 - Fixed get record of status type [#27](https://github.com/xmidt-org/codex-db/pull/27)
 - Improved cassandra connect logic [#27](https://github.com/xmidt-org/codex-db/pull/27)
@@ -47,7 +50,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [v0.1.0]
 - Initial creation, moved from: https://github.com/xmidt-org/codex-deploy
 
-[Unreleased]: https://github.com/xmidt-org/codex-db/compare/v0.5.1..HEAD
+[Unreleased]: https://github.com/xmidt-org/codex-db/compare/v0.5.2..HEAD
+[v0.5.2]: https://github.com/xmidt-org/codex-db/compare/v0.5.1..v0.5.2
 [v0.5.1]: https://github.com/xmidt-org/codex-db/compare/v0.5.0..v0.5.1
 [v0.5.0]: https://github.com/xmidt-org/codex-db/compare/v0.4.0..v0.5.0
 [v0.4.0]: https://github.com/xmidt-org/codex-db/compare/v0.3.3..v0.4.0

cassandra/db.go

@@ -220,17 +220,25 @@ func (c *Connection) GetStateHash(records []db.Record) (string, error) {
 	}
 	original := gocql.UUIDFromTime(time.Time{})
 	latest := original
+	originalBirthDate := int64(0)
+	latestBirthDate := originalBirthDate
 	for _, elem := range records {
 		uuid, err := gocql.ParseUUID(elem.RowID)
 		if err != nil {
+			if elem.BirthDate > latestBirthDate {
+				latestBirthDate = elem.BirthDate
+			}
 			continue
 		}
 		if uuid.Time().UnixNano() > latest.Time().UnixNano() {
 			latest = uuid
 		}
 	}
+	if latest == original && latestBirthDate == originalBirthDate {
+		return gocql.TimeUUID().String(), errors.New("no hash or birthdate found")
+	}
 	if latest == original {
-		return "", errors.New("no hash found")
+		return gocql.UUIDFromTime(time.Unix(0, latestBirthDate)).String(), errors.New("no hash found")
 	}
 	return latest.String(), nil
 }

cassandra/db_test.go

@@ -20,11 +20,14 @@ package cassandra
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
 	db "github.com/xmidt-org/codex-db"
 	"github.com/xmidt-org/webpa-common/xmetrics/xmetricstest"
 	"github.com/xmidt-org/wrp-go/wrp"
+	"github.com/yugabyte/gocql"
 	"testing"
 	"time"
 )
@@ -173,6 +176,7 @@ func TestGetRecordsOfType(t *testing.T) {
 }
 
 func TestGetLatestHash(t *testing.T) {
+	goodUUID := gocql.TimeUUID()
 	tests := []struct {
 		description  string
 		expectedHash string
@@ -210,16 +214,18 @@ func TestGetLatestHash(t *testing.T) {
 			hasError:     false,
 		},
 		{
-			description:  "empty record record",
-			expectedHash: "",
-			records:      []db.Record{{}},
+			description:  "empty record",
+			expectedHash: goodUUID.String(),
+			records:      []db.Record{{BirthDate: goodUUID.Time().UnixNano()}},
 			hasError:     true,
 		},
 	}
 
 	for _, tc := range tests {
 		t.Run(tc.description, func(t *testing.T) {
 			assert := assert.New(t)
+			require := require.New(t)
+
 			mockObj := new(mockFinder)
 			p := xmetricstest.NewProvider(nil, Metrics)
 			m := NewMeasures(p)
@@ -230,12 +236,22 @@ func TestGetLatestHash(t *testing.T) {
 
 			hash, err := dbConnection.GetStateHash(tc.records)
 			if tc.hasError {
+				fmt.Println(err)
 				assert.Error(err)
 			} else {
 				assert.NoError(err)
 			}
-			assert.Equal(tc.expectedHash, hash)
-			mockObj.AssertExpectations(t)
+			if hash != "" {
+				hashedTime, err := gocql.ParseUUID(hash)
+				require.NoError(err)
+				expectedTime, err := gocql.ParseUUID(tc.expectedHash)
+				require.NoError(err)
+
+				assert.Equal(expectedTime.Time().UnixNano(), hashedTime.Time().UnixNano())
+				mockObj.AssertExpectations(t)
+			} else {
+				assert.Equal(tc.expectedHash, hash)
+			}
 
 		})
 	}