[test-improver] Improve tests for auth package (GenerateRandomAPIKey)

internal/auth/apikey_test.go

@@ -1,6 +1,8 @@
 package auth_test
 
 import (
+	"encoding/hex"
+	"regexp"
 	"testing"
 
 	"github.com/github/gh-aw-mcpg/internal/auth"
@@ -22,3 +24,48 @@ func TestGenerateRandomAPIKey(t *testing.T) {
 	require.NoError(t, err)
 	assert.NotEqual(t, key, key2, "successive calls should produce unique keys")
 }
+
+// TestGenerateRandomAPIKey_IsValidHex verifies the returned key is a valid
+// hex-encoded string that decodes to exactly 32 bytes.
+func TestGenerateRandomAPIKey_IsValidHex(t *testing.T) {
+	key, err := auth.GenerateRandomAPIKey()
+	require.NoError(t, err)
+
+	decoded, decodeErr := hex.DecodeString(key)
+	require.NoError(t, decodeErr, "key should be valid hex-encoded string; got %q", key)
+	assert.Len(t, decoded, 32, "decoded key should be 32 bytes")
+}
+
+// TestGenerateRandomAPIKey_IsLowercaseHex verifies the key uses only lowercase
+// hex characters (0-9, a-f) as produced by hex.EncodeToString.
+func TestGenerateRandomAPIKey_IsLowercaseHex(t *testing.T) {
+	key, err := auth.GenerateRandomAPIKey()
+	require.NoError(t, err)
+
+	matched, matchErr := regexp.MatchString(`^[0-9a-f]{64}$`, key)
+	require.NoError(t, matchErr)
+	assert.True(t, matched, "key should consist of exactly 64 lowercase hex chars; got %q", key)
+}
+
+// TestGenerateRandomAPIKey_Uniqueness verifies that repeated calls produce
+// distinct keys, confirming that crypto/rand entropy is used.
+func TestGenerateRandomAPIKey_Uniqueness(t *testing.T) {
+	const n = 20
+	seen := make(map[string]bool, n)
+	for i := 0; i < n; i++ {
+		key, err := auth.GenerateRandomAPIKey()
+		require.NoError(t, err, "call %d: GenerateRandomAPIKey() should not fail", i+1)
+		assert.False(t, seen[key], "call %d: generated duplicate key %q", i+1, key)
+		seen[key] = true
+	}
+}
+
+// TestGenerateRandomAPIKey_LengthConsistency verifies that every call returns
+// a key of exactly 64 characters, regardless of call order.
+func TestGenerateRandomAPIKey_LengthConsistency(t *testing.T) {
+	for i := 0; i < 10; i++ {
+		key, err := auth.GenerateRandomAPIKey()
+		require.NoError(t, err, "call %d: GenerateRandomAPIKey() should not fail", i+1)
+		assert.Len(t, key, 64, "call %d: key should always be 64 characters", i+1)
+	}
+}