Improve encapsulation on SignatureBouncer

contracts/access/SignatureBouncer.sol

@@ -32,10 +32,13 @@ import "../ECRecovery.sol";
 contract SignatureBouncer is Ownable, RBAC {
   using ECRecovery for bytes32;
 
-  string public constant ROLE_BOUNCER = "bouncer";
-  uint internal constant METHOD_ID_SIZE = 4;
-  // signature size is 65 bytes (tightly packed v + r + s), but gets padded to 96 bytes
-  uint internal constant SIGNATURE_SIZE = 96;
+  // Name of the bouncer role.
+  string private constant ROLE_BOUNCER = "bouncer";
+  // Function selectors are 4 bytes long, as documented in
+  // https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector
+  uint256 private constant METHOD_ID_SIZE = 4;
+  // Signature size is 65 bytes (tightly packed v + r + s), but gets padded to 96 bytes
+  uint256 private constant SIGNATURE_SIZE = 96;
 
   /**
    * @dev requires that a valid signature of a bouncer was provided
@@ -64,6 +67,14 @@ contract SignatureBouncer is Ownable, RBAC {
     _;
   }
 
+  /**
+   * @dev Determine if an account has the bouncer role.
+   * @return true if the account is a bouncer, false otherwise.
+   */
+  function isBouncer(address _account) public view returns(bool) {
+    return hasRole(_account, ROLE_BOUNCER);
+  }
+
   /**
    * @dev allows the owner to add additional bouncer addresses
    */
@@ -153,6 +164,6 @@ contract SignatureBouncer is Ownable, RBAC {
     address signer = _hash
       .toEthSignedMessageHash()
       .recover(_signature);
-    return hasRole(signer, ROLE_BOUNCER);
+    return isBouncer(signer);
   }
 }

test/access/SignatureBouncer.test.js

@@ -16,7 +16,6 @@ const INVALID_SIGNATURE = '0xabcd';
 contract('Bouncer', function ([_, owner, anyone, bouncerAddress, authorizedUser]) {
   beforeEach(async function () {
     this.bouncer = await Bouncer.new({ from: owner });
-    this.roleBouncer = await this.bouncer.ROLE_BOUNCER();
   });
 
   context('management', function () {
@@ -26,7 +25,7 @@ contract('Bouncer', function ([_, owner, anyone, bouncerAddress, authorizedUser]
 
     it('allows the owner to add a bouncer', async function () {
       await this.bouncer.addBouncer(bouncerAddress, { from: owner });
-      (await this.bouncer.hasRole(bouncerAddress, this.roleBouncer)).should.equal(true);
+      (await this.bouncer.isBouncer(bouncerAddress)).should.equal(true);
     });
 
     it('does not allow adding an invalid address', async function () {