refactor(ctb): Make canRemove a public function

packages/contracts-bedrock/src/Safe/LivenessModule.sol

@@ -98,6 +98,14 @@ contract LivenessModule is ISemver {
         fallbackOwner_ = FALLBACK_OWNER;
     }
 
+    /// @notice Checks if the owner can be removed
+    /// @param _owner The owner to be removed
+    /// @return canRemove_ bool indicating if the owner can be removed
+    function canRemove(address _owner) public view returns (bool canRemove_) {
+        require(SAFE.isOwner(_owner), "LivenessModule: the owner to remove must be an owner of the Safe");
+        canRemove_ = LIVENESS_GUARD.lastLive(_owner) + LIVENESS_INTERVAL < block.timestamp;
+    }
+
     /// @notice This function can be called by anyone to remove a set of owners that have not signed a transaction
     ///         during the liveness interval. If the number of owners drops below the minimum, then all owners
     ///         must be removed.
@@ -111,7 +119,7 @@ contract LivenessModule is ISemver {
         for (uint256 i = 0; i < _previousOwners.length; i++) {
             ownersCount--;
             if (ownersCount >= MIN_OWNERS) {
-                require(_canRemove(_ownersToRemove[i]), "LivenessModule: the owner to remove has signed recently");
+                require(canRemove(_ownersToRemove[i]), "LivenessModule: the owner to remove has signed recently");
             }
 
             _removeOwner({
@@ -170,13 +178,6 @@ contract LivenessModule is ISemver {
         );
     }
 
-    /// @notice Checks if the owner can be removed
-    /// @param _owner The owner to be removed
-    /// @return canRemove_ bool indicating if the owner can be removed
-    function _canRemove(address _owner) internal view returns (bool canRemove_) {
-        canRemove_ = LIVENESS_GUARD.lastLive(_owner) + LIVENESS_INTERVAL < block.timestamp;
-    }
-
     /// @notice A FREI-PI invariant check enforcing requirements on number of owners and threshold.
     function _verifyFinalState() internal view {
         address[] memory owners = SAFE.getOwners();

packages/contracts-bedrock/test/LivenessModule.t.sol

@@ -105,6 +105,24 @@ contract LivenessModule_Getters_Test is LivenessModule_TestInit {
     }
 }
 
+contract LivenessModule_CanRemove_TestFail is LivenessModule_TestInit {
+    /// @dev Tests if canRemove work correctly
+    function test_canRemove_notSafeOwner_reverts() external {
+        address nonOwner = makeAddr("nonOwner");
+        vm.expectRevert("LivenessModule: the owner to remove must be an owner of the Safe");
+        livenessModule.canRemove(nonOwner);
+    }
+}
+
+contract LivenessModule_CanRemove_Test is LivenessModule_TestInit {
+    /// @dev Tests if canRemove work correctly
+    function test_canRemove_works() external {
+        _warpPastLivenessInterval();
+        bool canRemove = livenessModule.canRemove(safeInstance.owners[0]);
+        assertTrue(canRemove);
+    }
+}
+
 contract LivenessModule_Get75PercentThreshold_Test is LivenessModule_TestInit {
     /// @dev check the return values of the get75PercentThreshold function against manually
     ///      calculated values.