feat: added stringy function for the custom royalty fee (#986) (#1001)

Signed-off-by: HusseinYasser <husseinyasser388@gmail.com>

Author: HusseinYasser

CHANGELOG.md

@@ -17,6 +17,7 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 - Add inactivity bot workflow to unassign stale issue assignees (#952)
 - Made custom fraction fee end to end
 - Added Acceptance Criteria section to Good First Issue template for better contributor guidance (#997)
+- Added __str__() to CustomRoyaltyFee and updated examples and tests accordingly (#986)
 
 ### Changed
 

examples/tokens/custom_royalty_fee.py

@@ -20,13 +20,7 @@ def custom_royalty_fee():
         fee_collector_account_id=AccountId(0, 0, 456),
         all_collectors_are_exempt=True,
     )
-    print("\nCustomRoyaltyFee:")
-    print(f"Numerator: {royalty_fee.numerator}")
-    print(f"Denominator: {royalty_fee.denominator}")
-    print(f"Fallback Fee Amount: {royalty_fee.fallback_fee.amount if royalty_fee.fallback_fee is not None else 'None'}")
-    print(f"Fallback Fee Denominating Token ID: {royalty_fee.fallback_fee.denominating_token_id if royalty_fee.fallback_fee is not None else 'None'}")
-    print(f"Fee Collector Account ID: {royalty_fee.fee_collector_account_id}")
-    print(f"All Collectors Exempt: {royalty_fee.all_collectors_are_exempt}")
+    print(royalty_fee)
 
     # Convert to protobuf
     royalty_fee_proto = royalty_fee._to_proto()

src/hiero_sdk_python/tokens/custom_royalty_fee.py

@@ -150,4 +150,27 @@ def _from_proto(cls, proto_fee) -> "CustomRoyaltyFee":
             fallback_fee=fallback_fee,
             fee_collector_account_id=fee_collector_account_id,
             all_collectors_are_exempt=proto_fee.all_collectors_are_exempt
-        )
+        )
+
+    def __str__(self) -> str:
+        """Returns a string representation of the CustomRoyaltyFee.
+
+        Includes the numerator, denominator, fallback fee details (if any),
+        fee collector account ID, and exemption status.
+
+        Returns:
+            str: A human-readable string representation of the royalty fee.
+        """
+        fallback_fee_amount = self.fallback_fee.amount if self.fallback_fee else "None"
+        fallback_fee_token_id = self.fallback_fee.denominating_token_id if self.fallback_fee else "None"
+
+        lines = [
+            f"CustomRoyaltyFee:",
+            f"   Numerator = {self.numerator}",
+            f"   Denominator = {self.denominator}",
+            f"   Fallback Fee Amount = {fallback_fee_amount}",
+            f"   Fallback Fee Denominating Token ID = {fallback_fee_token_id}",
+            f"   Fee Collector Account ID = {self.fee_collector_account_id}",
+            f"   All Collectors Are Exempt = {self.all_collectors_are_exempt}",
+        ]
+        return "\n".join(lines)

tests/unit/test_custom_fee.py

@@ -150,4 +150,53 @@ def test_custom_royalty_fee():
     assert new_fee.all_collectors_are_exempt is True
     assert isinstance(new_fee.fallback_fee, CustomFixedFee)
     assert new_fee.fallback_fee.amount == 50
-    assert new_fee.fallback_fee.denominating_token_id == TokenId(0, 0, 789)
+    assert new_fee.fallback_fee.denominating_token_id == TokenId(0, 0, 789)
+
+@pytest.mark.parametrize(
+        "custom_royalty_fee, expected_str",
+        [
+            (
+                CustomRoyaltyFee(
+                   numerator=3,
+                   denominator=20,
+                   fallback_fee=None,
+                   fee_collector_account_id=None,
+                   all_collectors_are_exempt=True,
+                ),
+                "\n".join([
+                    "CustomRoyaltyFee:",
+                    "   Numerator = 3",
+                    "   Denominator = 20",
+                    "   Fallback Fee Amount = None",
+                    "   Fallback Fee Denominating Token ID = None",
+                    "   Fee Collector Account ID = None",
+                    "   All Collectors Are Exempt = True",
+                ])
+            ),
+            (
+                CustomRoyaltyFee(
+                    numerator=7,
+                    denominator=100,
+                    fallback_fee=CustomFixedFee(
+                        amount=30,
+                        denominating_token_id=TokenId(0, 0, 123),
+                    ),
+                    fee_collector_account_id=AccountId(0, 0, 456),
+                    all_collectors_are_exempt=False,
+                ),
+                "\n".join([
+                    "CustomRoyaltyFee:",
+                    "   Numerator = 7",
+                    "   Denominator = 100",
+                    "   Fallback Fee Amount = 30",
+                    "   Fallback Fee Denominating Token ID = 0.0.123",
+                    "   Fee Collector Account ID = 0.0.456",
+                    "   All Collectors Are Exempt = False",
+                ])
+            )
+        ]
+)
+def test_custom_royalty_fee_str(custom_royalty_fee: CustomRoyaltyFee, expected_str: str):
+    """Test the string representation of CustomRoyaltyFee."""
+    fee_str = str(custom_royalty_fee)
+    assert fee_str == expected_str