diff --git a/pkg/workload/core_test.go b/pkg/workload/core_test.go
new file mode 100644
index 00000000..ee2b3b2a
--- /dev/null
+++ b/pkg/workload/core_test.go
@@ -0,0 +1,74 @@
+package workload
+
+import (
+	"github.com/magiconair/properties"
+	"github.com/pingcap/go-ycsb/pkg/generator"
+	"github.com/pingcap/go-ycsb/pkg/ycsb"
+	"sync"
+	"testing"
+)
+
+func Test_core_nextKeyNum(t *testing.T) {
+	type fields struct {
+		p                            *properties.Properties
+		table                        string
+		fieldCount                   int64
+		fieldNames                   []string
+		fieldLengthGenerator         ycsb.Generator
+		readAllFields                bool
+		writeAllFields               bool
+		dataIntegrity                bool
+		keySequence                  ycsb.Generator
+		operationChooser             *generator.Discrete
+		keyChooser                   ycsb.Generator
+		fieldChooser                 ycsb.Generator
+		transactionInsertKeySequence *generator.AcknowledgedCounter
+		scanLength                   ycsb.Generator
+		orderedInserts               bool
+		recordCount                  int64
+		zeroPadding                  int64
+		insertionRetryLimit          int64
+		insertionRetryInterval       int64
+		valuePool                    sync.Pool
+	}
+	type args struct {
+		state *coreState
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   int64
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := &core{
+				p:                            tt.fields.p,
+				table:                        tt.fields.table,
+				fieldCount:                   tt.fields.fieldCount,
+				fieldNames:                   tt.fields.fieldNames,
+				fieldLengthGenerator:         tt.fields.fieldLengthGenerator,
+				readAllFields:                tt.fields.readAllFields,
+				writeAllFields:               tt.fields.writeAllFields,
+				dataIntegrity:                tt.fields.dataIntegrity,
+				keySequence:                  tt.fields.keySequence,
+				operationChooser:             tt.fields.operationChooser,
+				keyChooser:                   tt.fields.keyChooser,
+				fieldChooser:                 tt.fields.fieldChooser,
+				transactionInsertKeySequence: tt.fields.transactionInsertKeySequence,
+				scanLength:                   tt.fields.scanLength,
+				orderedInserts:               tt.fields.orderedInserts,
+				recordCount:                  tt.fields.recordCount,
+				zeroPadding:                  tt.fields.zeroPadding,
+				insertionRetryLimit:          tt.fields.insertionRetryLimit,
+				insertionRetryInterval:       tt.fields.insertionRetryInterval,
+				valuePool:                    tt.fields.valuePool,
+			}
+			if got := c.nextKeyNum(tt.args.state); got != tt.want {
+				t.Errorf("nextKeyNum() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}