diff --git a/day-15/go.mod b/day-15/go.mod
index 228e1e8..6bcf2ed 100644
--- a/day-15/go.mod
+++ b/day-15/go.mod
@@ -5,6 +5,12 @@ go 1.21.5
 require (
 	github.com/elliotchance/orderedmap/v2 v2.2.0
 	github.com/sirupsen/logrus v1.9.3
+	github.com/stretchr/testify v1.7.1
 )
 
-require golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+)
diff --git a/day-15/go.sum b/day-15/go.sum
index 70c7aac..49660a1 100644
--- a/day-15/go.sum
+++ b/day-15/go.sum
@@ -13,6 +13,7 @@ github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMT
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/day-15/hasher_test.go b/day-15/hasher_test.go
new file mode 100644
index 0000000..fdca86f
--- /dev/null
+++ b/day-15/hasher_test.go
@@ -0,0 +1,29 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHasher(t *testing.T) {
+	//t.Skip("skipping test")
+
+	hash := newHasher()
+
+	t.Run("Should produce a hash value 30", func(t *testing.T) {
+		assert.Equal(t, 30, hash.run("rn=1"))
+	})
+
+	t.Run("Should produce a hash value 253", func(t *testing.T) {
+		assert.Equal(t, 253, hash.run("cm-"))
+	})
+
+	t.Run("Should produce a hash value 0", func(t *testing.T) {
+		assert.Equal(t, 0, hash.run("rn"))
+	})
+
+	t.Run("Should produce a hash value 3", func(t *testing.T) {
+		assert.Equal(t, 3, hash.run("pc"))
+	})
+}