diff --git a/.mockery.yaml b/.mockery.yaml
new file mode 100644
index 0000000..0df4c1b
--- /dev/null
+++ b/.mockery.yaml
@@ -0,0 +1,11 @@
+with-expecter: true
+dir: "{{.InterfaceDir}}/mocks"
+mockname: "Mock{{.InterfaceName}}"
+outpkg: "{{.PackageName}}"
+filename: "mock_{{.InterfaceName | snakecase}}.go"
+packages:
+  github.com/word-of-wisdom/internal/pow:
+    interfaces:
+      Generator:
+      Verifier:
+      Solver:
\ No newline at end of file
diff --git a/go.mod b/go.mod
index 54ac4fd..96cd041 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module word-of-wisdom
 
 go 1.24.3
+
+require github.com/stretchr/testify v1.10.0 // indirect
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..7bfdabe
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
diff --git a/internal/pow/test_utils.go b/internal/pow/test_utils.go
new file mode 100644
index 0000000..20b11df
--- /dev/null
+++ b/internal/pow/test_utils.go
@@ -0,0 +1,65 @@
+package pow
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"time"
+)
+
+// TestConfig returns a configuration suitable for testing
+func TestConfig() *Config {
+	secret := make([]byte, 32)
+	rand.Read(secret)
+
+	return &Config{
+		DefaultDifficulty:     4,
+		MaxDifficulty:         10,
+		MinDifficulty:         3,
+		ChallengeTTL:          5 * time.Minute,
+		HMACSecret:            secret,
+		Resource:              "quotes",
+		LoadAdjustmentBits:    1,
+		FailurePenaltyBits:    2,
+		MaxFailurePenaltyBits: 6,
+	}
+}
+
+// TestChallenge returns a valid challenge for testing
+func TestChallenge() *Challenge {
+	return &Challenge{
+		Timestamp:  time.Now().Unix(),
+		Difficulty: 4,
+		Resource:   "quotes",
+		Random:     "a1b2c3d4e5f6",
+		HMAC:       "", // To be filled by generator
+	}
+}
+
+// TestSolution returns a valid solution for testing
+func TestSolution() *Solution {
+	return &Solution{
+		Challenge: *TestChallenge(),
+		Nonce:     "42",
+	}
+}
+
+// RandomHex generates a random hex string of given length
+func RandomHex(length int) string {
+	bytes := make([]byte, length/2)
+	rand.Read(bytes)
+	return hex.EncodeToString(bytes)
+}
+
+// ExpiredChallenge returns a challenge that has expired
+func ExpiredChallenge() *Challenge {
+	challenge := TestChallenge()
+	challenge.Timestamp = time.Now().Add(-10 * time.Minute).Unix()
+	return challenge
+}
+
+// FutureChallenge returns a challenge with future timestamp
+func FutureChallenge() *Challenge {
+	challenge := TestChallenge()
+	challenge.Timestamp = time.Now().Add(10 * time.Minute).Unix()
+	return challenge
+}