diff --git a/gen_test_data.py b/gen_test_data.py
index 12f555e..2bdee5e 100644
--- a/gen_test_data.py
+++ b/gen_test_data.py
@@ -24,6 +24,11 @@ def total_leading_zeros(hash):
 
     return to_return
 
+def to_hex_list(bt: bytes) -> list:
+    r = []
+    for b in bt:
+        r.append(f'0x{hex(b)[2:].upper()}')
+    return r
 
 def gen(hash, difficulty):
     difficulty = total_leading_zeros(difficulty)
@@ -37,9 +42,9 @@ def gen(hash, difficulty):
         ghash_leadin_zeros = total_leading_zeros(generated_hash)
 
         if ghash_leadin_zeros >= difficulty:
-            print(pow, True)
+            print(', '.join(to_hex_list(pow)), True)
         else:
-            print(pow, False)
+            print(', '.join(to_hex_list(pow)), False)
 
 
 gen(hashlib.sha256(b'text').digest(),
diff --git a/tests/tools_test.rs b/tests/tools_test.rs
index 70cf495..9c235f1 100644
--- a/tests/tools_test.rs
+++ b/tests/tools_test.rs
@@ -1,4 +1,15 @@
-use blockchaintree::tools;
+use blockchaintree::tools::{self, check_pow};
 
 #[test]
-fn pow_test() {}
+fn check_pow_test() {
+    let hash: [u8; 32] = [0x98, 0x2D, 0x9E, 0x3E, 0xB9, 0x96, 0xF5, 0x59, 0xE6, 0x33, 0xF4, 0xD1, 0x94, 0xDE, 0xF3, 0x76, 0x1D, 0x90, 0x9F, 0x5A, 0x3B, 0x64, 0x7D, 0x1A, 0x85, 0x1F, 0xEA, 0xD6, 0x7C, 0x32, 0xC9, 0xD1];
+
+    assert_eq!(
+        check_pow(&hash, &[0xF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF], &[0x0, 0x7A, 0x9, 0xDE, 0x81, 0x32, 0x58, 0x4F, 0x6D, 0xE8]),
+        false
+    );
+    assert_eq!(
+        check_pow(&hash, &[0xF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF], &[0x3A, 0x91, 0x24, 0x45, 0xC9, 0x65, 0x60, 0xD5, 0x1E, 0x69]),
+        true
+    );
+}
\ No newline at end of file