update .getCapability() to return nil if cap disallowed + tests (#160)

Closes: #159

contracts/HybridCustody.cdc

@@ -574,7 +574,7 @@ pub contract HybridCustody {
 
         /// The main function to a child account's capabilities from a parent account. When a PrivatePath type is used,
         /// the CapabilityFilter will be borrowed and the Capability being returned will be checked against it to
-        /// ensure that borrowing is permitted.
+        /// ensure that borrowing is permitted. If not allowed, nil is returned.
         /// Also know that this method retrieves Capabilities via the CapabilityFactory path. To retrieve arbitrary 
         /// Capabilities, see `getPrivateCapFromDelegator()` and `getPublicCapFromDelegator()` which use the
         /// `Delegator` retrieval path.
@@ -588,11 +588,15 @@ pub contract HybridCustody {
             }
 
             let acct = child.borrowAccount()
-
             let cap = f!.getCapability(acct: acct, path: path)
-
-            if path.getType() == Type<PrivatePath>() {
-                assert(self.filter.borrow()!.allowed(cap: cap), message: "requested capability is not allowed")
+
+            // Check that private capabilities are allowed by either internal or manager filter (if assigned)
+            // If not allowed, return nil
+            if path.getType() == Type<PrivatePath>() && (
+                self.filter.borrow()!.allowed(cap: cap) == false || 
+                (self.getManagerCapabilityFilter()?.allowed(cap: cap) ?? true) == false
+            ) {
+                return nil
             }
 
             return cap

scripts/test/get_nft_provider_capability_optional.cdc

@@ -0,0 +1,20 @@
+import "HybridCustody"
+
+import "NonFungibleToken"
+import "MetadataViews"
+import "ExampleNFT"
+
+// Verify that a child address borrowed as a child will let the parent borrow an NFT provider capability
+pub fun main(parent: Address, child: Address, returnsNil: Bool): Bool {
+    let acct = getAuthAccount(parent)
+    let manager = acct.borrow<&HybridCustody.Manager>(from: HybridCustody.ManagerStoragePath)
+        ?? panic("manager does not exist")
+
+    let childAcct = manager.borrowAccount(addr: child) ?? panic("child account not found")
+
+    let collectionData = ExampleNFT.resolveView(Type<MetadataViews.NFTCollectionData>())! as! MetadataViews.NFTCollectionData
+
+    let nakedCap = childAcct.getCapability(path: collectionData.providerPath, type: Type<&{NonFungibleToken.Provider}>())
+
+    return returnsNil ? nakedCap == nil : nakedCap?.borrow<&{NonFungibleToken.Provider}>() != nil
+}

test/CapabilityFactory_tests.cdc

@@ -206,12 +206,4 @@ pub fun findExampleNFTCollectionType(_ owner: Test.Account) {
     assert(borrowed, message: "failed to borrow delegator")
 }
 
-pub fun expectScriptFailure(_ scriptName: String, _ arguments: [AnyStruct]): String {
-    let scriptCode = loadCode(scriptName, "scripts")
-    let scriptResult = blockchain.executeScript(scriptCode, arguments)
-
-    assert(scriptResult.error != nil, message: "script error was expected but there is no error message")
-    return scriptResult.error!.message
-}
-
 // END SECTION - scripts used in tests

test/HybridCustody_tests.cdc

@@ -179,6 +179,33 @@ pub fun testChildAccount_getCapability() {
     scriptExecutor("hybrid-custody/get_nft_provider_capability.cdc", [parent.address, child.address])
 }
 
+pub fun testChildAccount_getCapabilityReturnsNil() {
+    let dev = blockchain.createAccount()
+    let child = blockchain.createAccount()
+    let parent = blockchain.createAccount()
+
+    // Setup NFT Filter & Factory
+    txExecutor("dev-setup/setup_nft_filter_and_factory_manager.cdc", [dev], [accounts[exampleNFT]!.address, exampleNFT], nil, nil)
+    // Setup OwnedAccount in child account
+    txExecutor("hybrid-custody/setup_owned_account.cdc", [child], [nil, nil, nil], nil, nil)
+    // Publish ChildAccount for parent, factory & filter found in previously configured dev accoun
+    txExecutor("hybrid-custody/publish_to_parent.cdc", [child], [parent.address, dev.address, dev.address], nil, nil)
+    // Redeem ChildAccount as parent
+    txExecutor("hybrid-custody/redeem_account.cdc", [parent], [child.address, nil, nil], nil, nil)
+
+    // Configure NFT Collection in child account
+    setupNFTCollection(child)
+    // ExampleNFT Provider is allowed by Allowlist Filter, so should return valid Capability
+    let returnsValidCap = scriptExecutor("test/get_nft_provider_capability_optional.cdc", [parent.address, child.address, false])! as! Bool
+    Test.assertEqual(true, returnsValidCap)
+    // Remove types from filter
+    removeAllFilterTypes(dev, FilterKindAllowList)
+
+    // ExampleNFT Provider has been removed from Allowlist Filter - getCapability() should return nil
+    let returnsNil = scriptExecutor("test/get_nft_provider_capability_optional.cdc", [parent.address, child.address, true])! as! Bool
+    Test.assertEqual(true, returnsNil)
+}
+
 pub fun testChildAccount_getPublicCapability() {
     let child = blockchain.createAccount()
     let parent = blockchain.createAccount()
@@ -325,7 +352,7 @@ pub fun testGetCapability_ManagerFilterAllowed() {
     setManagerFilterOnChild(child: child, parent: parent, filterAddress: filter.address)
 
     let error = expectScriptFailure("hybrid-custody/get_nft_provider_capability.cdc", [parent.address, child.address])
-    assert(contains(error, "Capability is not allowed by this account's Parent"), message: "failed to find expected error message")
+    assert(contains(error, "capability not found"), message: "failed to find expected error message")
 
     addTypeToFilter(filter, FilterKindAllowList, nftIdentifier)
     scriptExecutor("hybrid-custody/get_nft_provider_capability.cdc", [parent.address, child.address])
@@ -354,7 +381,7 @@ pub fun testAllowlistFilterRemoveAllTypes() {
     removeAllFilterTypes(filter, FilterKindAllowList)
 
     let error = expectScriptFailure("hybrid-custody/get_nft_provider_capability.cdc", [parent.address, child.address])
-    assert(contains(error, "Capability is not allowed by this account's Parent"), message: "failed to find expected error message")
+    assert(contains(error, "capability not found"), message: "failed to find expected error message")
 }
 
 pub fun testDenyListFilterRemoveAllTypes() {
@@ -375,7 +402,7 @@ pub fun testDenyListFilterRemoveAllTypes() {
     setManagerFilterOnChild(child: child, parent: parent, filterAddress: filter.address)
 
     let error = expectScriptFailure("hybrid-custody/get_nft_provider_capability.cdc", [parent.address, child.address])
-    assert(contains(error, "Capability is not allowed by this account's Parent"), message: "failed to find expected error message")
+    assert(contains(error, "capability not found"), message: "failed to find expected error message")
 
 
     removeAllFilterTypes(filter, FilterKindDenyList)
@@ -400,7 +427,7 @@ pub fun testGetCapability_ManagerFilterNotAllowed() {
     setManagerFilterOnChild(child: child, parent: parent, filterAddress: filter.address)
 
     let error = expectScriptFailure("hybrid-custody/get_nft_provider_capability.cdc", [parent.address, child.address])
-    assert(contains(error, "Capability is not allowed by this account's Parent"), message: "failed to find expected error message")
+    assert(contains(error, "capability not found"), message: "failed to find expected error message")
 }
 
 pub fun testGetPrivateCapabilityFromDelegator() {
@@ -813,7 +840,7 @@ pub fun testSetDefaultManagerFilter() {
     addTypeToFilter(filter, FilterKindDenyList, nftIdentifier)
 
     let error = expectScriptFailure("hybrid-custody/get_nft_provider_capability.cdc", [parent.address, child2.address])
-    assert(contains(error, "Capability is not allowed by this account's Parent"), message: "failed to find expected error message")
+    assert(contains(error, "capability not found"), message: "failed to find expected error message")
 }
 
 pub fun testPublishToParent_alreadyExists() {
@@ -1074,14 +1101,6 @@ pub fun getTestAccount(_ name: String): Test.Account {
     return accounts[name]!
 }
 
-pub fun expectScriptFailure(_ scriptName: String, _ arguments: [AnyStruct]): String {
-    let scriptCode = loadCode(scriptName, "scripts")
-    let scriptResult = blockchain.executeScript(scriptCode, arguments)
-
-    assert(scriptResult.error != nil, message: "script error was expected but there is no error message")
-    return scriptResult.error!.message
-}
-
 pub fun setup() {
     // actual test accounts
     let parent = blockchain.createAccount()

test/test_helpers.cdc

@@ -36,6 +36,14 @@ pub fun scriptExecutor(_ scriptName: String, _ arguments: [AnyStruct]): AnyStruc
     return scriptResult.returnValue
 }
 
+pub fun expectScriptFailure(_ scriptName: String, _ arguments: [AnyStruct]): String {
+    let scriptCode = loadCode(scriptName, "scripts")
+    let scriptResult = blockchain.executeScript(scriptCode, arguments)
+
+    assert(scriptResult.error != nil, message: "script error was expected but there is no error message")
+    return scriptResult.error!.message
+}
+
 pub fun txExecutor(_ txName: String, _ signers: [Test.Account], _ arguments: [AnyStruct], _ expectedError: String?, _ expectedErrorType: ErrorType?): Bool {
     let txCode = loadCode(txName, "transactions")