feat: add tests

Author: heueristik

contracts/foundry.toml

@@ -59,7 +59,7 @@ test = "test"
 allow_internal_expect_revert = true
 
 [fuzz]
-runs = 1_000
+runs = 1_00000
 
 [profile.ci]
 fuzz = { runs = 1_000 }

contracts/test/proofs/DeltaProof.t.sol

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.30;
 
+import {EllipticCurve} from "@elliptic-curve-solidity/contracts/EllipticCurve.sol";
 import {Test} from "forge-std/Test.sol";
 
 import {Delta} from "../../src/libs/proving/Delta.sol";
@@ -302,6 +303,66 @@ contract DeltaProofTest is Test {
         DeltaFuzzing.verify({proof: proof, instance: deltaAcc, verifyingKey: verifyingKey});
     }
 
+    function test_add_reverts_if_the_second_point_is_not_on_the_curve(uint8 k) public {
+        // Generate a random point on the curve.
+        Delta.Point memory p1 = _mul({p: Delta.Point({x: Delta._GX, y: Delta._GY}), k: k});
+        assertTrue(
+            EllipticCurve.isOnCurve({_x: p1.x, _y: p1.y, _aa: Delta._AA, _bb: Delta._BB, _pp: Delta._PP}),
+            "Point 1 must be on the curve."
+        );
+
+        Delta.Point memory p2 = Delta.zero();
+
+        // Attempt to add a point being not on the curve
+        vm.expectRevert(abi.encodeWithSelector(Delta.PointNotOnCurve.selector, p2), address(this));
+        p1.add(p2);
+    }
+
+    function test_add_adding_two_curve_points_produces_a_point_on_the_curve(uint8 k1, uint8 k2) public pure {
+        // Generate two random points on the curve.
+        Delta.Point memory p1 = _mul({p: Delta.Point({x: Delta._GX, y: Delta._GY}), k: k1});
+        assertTrue(
+            EllipticCurve.isOnCurve({_x: p1.x, _y: p1.y, _aa: Delta._AA, _bb: Delta._BB, _pp: Delta._PP}),
+            "Point 1 must be on the curve."
+        );
+
+        Delta.Point memory p2 = _mul({p: Delta.Point({x: Delta._GX, y: Delta._GY}), k: k2});
+        assertTrue(
+            EllipticCurve.isOnCurve({_x: p2.x, _y: p2.y, _aa: Delta._AA, _bb: Delta._BB, _pp: Delta._PP}),
+            "Point 2 must be on the curve."
+        );
+
+        // Add the two points.
+        Delta.Point memory sum = Delta.add(p1, p2);
+        assertTrue(
+            EllipticCurve.isOnCurve({_x: sum.x, _y: sum.y, _aa: Delta._AA, _bb: Delta._BB, _pp: Delta._PP}),
+            "Sum must be on the curve."
+        );
+    }
+
+    function test_add_adding_a_curve_point_to_zero_produces_a_point_on_the_curve(uint8 k) public pure {
+        Delta.Point memory zero = Delta.zero();
+
+        // Generate a random point on the curve.
+        Delta.Point memory p = _mul({p: Delta.Point({x: Delta._GX, y: Delta._GY}), k: k});
+        assertTrue(
+            EllipticCurve.isOnCurve({_x: p.x, _y: p.y, _aa: Delta._AA, _bb: Delta._BB, _pp: Delta._PP}),
+            "The point must be on the curve."
+        );
+
+        // Add the two points.
+        Delta.Point memory sum = zero.add(p);
+        assertTrue(
+            EllipticCurve.isOnCurve({_x: sum.x, _y: sum.y, _aa: Delta._AA, _bb: Delta._BB, _pp: Delta._PP}),
+            "Sum must be on the curve."
+        );
+    }
+
+    function test_zero_is_not_on_the_curve() public pure {
+        Delta.Point memory p2 = Delta.zero();
+        assertFalse(EllipticCurve.isOnCurve({_x: p2.x, _y: p2.y, _aa: Delta._AA, _bb: Delta._BB, _pp: Delta._PP}));
+    }
+
     function test_verify_example_delta_proof() public pure {
         Transaction memory txn = TransactionExample.transaction();