add tests for removing blocks

Author: arik-so

xcode/DirectBindingsApp/DirectBindingsApp/app-batteries/BlockchainObserver.swift

@@ -195,18 +195,24 @@ class BlockchainObserver {
 
 		// create an array of the new blocks
 		var addedBlocks = [RPCBlockDetails]()
-		for addedBlockHeight in (knownChaintip.height + 1)...currentChaintipHeight {
-			let addedBlockHash = try await self.getBlockHashHex(height: addedBlockHeight)
-			let addedBlock = try await self.getBlock(hash: addedBlockHash)
-			addedBlocks.append(addedBlock)
+		if knownChaintip.height < currentChaintipHeight {
+			// without this precondition, the range won't even work to begin with
+			for addedBlockHeight in (knownChaintip.height + 1)...currentChaintipHeight {
+				let addedBlockHash = try await self.getBlockHashHex(height: addedBlockHeight)
+				let addedBlock = try await self.getBlock(hash: addedBlockHash)
+				addedBlocks.append(addedBlock)
+			}
 		}
 
 		while addedBlocks.isEmpty || addedBlocks.first!.previousblockhash != self.connectedBlocks.last!.hash {
 			// we must keep popping until it matches
 			let trimmedLocalTip = try await self.disconnectBlock()
-			let reorgedBlockHash = try await self.getBlockHashHex(height: trimmedLocalTip.height)
-			let reorgedBlock = try await self.getBlock(hash: reorgedBlockHash)
-			addedBlocks.insert(reorgedBlock, at: 0)
+			if trimmedLocalTip.height <= currentChaintipHeight {
+				// if the trimmed block is simply gone, we cannot retrieve the current block hash hex
+				let reorgedBlockHash = try await self.getBlockHashHex(height: trimmedLocalTip.height)
+				let reorgedBlock = try await self.getBlock(hash: reorgedBlockHash)
+				addedBlocks.insert(reorgedBlock, at: 0)
+			}
 		}
 
 		for addedBlock in addedBlocks {
@@ -247,7 +253,7 @@ class BlockchainObserver {
 			}
 		}
 
-		print("connecting block \(block.height) with hex: \(block.hash)")
+		// print("connecting block \(block.height) with hex: \(block.hash)")
 
 		if self.chainListeners.count > 0 {
 			let binary = try await self.getBlockBinary(hash: block.hash)

xcode/DirectBindingsApp/DirectBindingsApp/app-batteries/RegtestBlockchainManager.swift

@@ -29,4 +29,14 @@ class RegtestBlockchainManager: BlockchainObserver {
         return result
     }
 
+    /**
+     Invalidate or un-mine a block
+     - Parameter hash: The block hash hex to invalidate
+     - Returns:
+     - Throws:
+     */
+    public func unmineBlock(hash: String) async throws {
+        let response = try await self.callRpcMethod(method: "invalidateblock", params: [hash])
+    }
+
 }

xcode/DirectBindingsApp/DirectBindingsAppTests/test-batteries/bitcoin/BitcoinTests.swift

@@ -123,7 +123,7 @@ public class BitcoinTests: XCTestCase {
 		// let address = try await rpcInterface.generateAddress()
 		// let details = try await rpcInterface.mineBlocks(number: 1, coinbaseDestinationAddress: address)
 		let helpDetails = try await rpcInterface.getHelp()
-		print(helpDetails)
+		// print(helpDetails)
 
 		let exampleFundingTx: [UInt8] = [1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 255, 255, 255, 0, 255, 255, 255, 255, 1, 160, 134, 1, 0, 0, 0, 0, 0, 34, 0, 32, 15, 45, 153, 123, 98, 37, 242, 142, 113, 51, 126, 45, 206, 175, 66, 247, 173, 2, 141, 2, 27, 84, 38, 188, 34, 74, 82, 164, 28, 229, 39, 139, 1, 1, 1, 0, 0, 0, 0]
 
@@ -132,16 +132,18 @@ public class BitcoinTests: XCTestCase {
 
 		class Listener: BlockchainListener {
 			var initializationComplete = false
-			var newBlockDetected = false
+			var newBlocksDetected = 0
+			var blocksLost = 0
 
 			func blockConnected(block: [UInt8], height: UInt32) {
 				if self.initializationComplete {
-					self.newBlockDetected = true
+					self.newBlocksDetected += 1
 				}
 				print("block connected at height \(height): \(block)")
 			}
 
 			func blockDisconnected(header: [UInt8]?, height: UInt32) {
+				self.blocksLost += 1
 				print("block disconnected from height \(height): \(header)")
 			}
 		}
@@ -157,10 +159,36 @@ public class BitcoinTests: XCTestCase {
 		let exampleOutputScript: [UInt8] = [0, 32, 200, 194, 75, 55, 227, 33, 251, 71, 196, 33, 177, 196, 155, 145, 17, 78, 244, 226, 155, 141, 216, 230, 180, 183, 149, 172, 116, 249, 56, 6, 118, 255]
 		let scriptInfo = try await rpcInterface.decodeScript(script: exampleOutputScript)
 		let outputAddress = (scriptInfo["addresses"] as! [String]).first!
+		try await rpcInterface.mineBlocks(number: 1, coinbaseDestinationAddress: testAddress)
 		try await rpcInterface.mineBlocks(number: 1, coinbaseDestinationAddress: outputAddress)
+
 		// sleep for six seconds
 		try await Task.sleep(nanoseconds: 6_000_000_000)
-		XCTAssertEqual(listener.newBlockDetected, true)
+		XCTAssertEqual(listener.newBlocksDetected, 2)
+		XCTAssertEqual(listener.blocksLost, 0)
+
+		do {
+			let testAddress = try await rpcInterface.generateAddress()
+			let chaintip = try await rpcInterface.getChaintipHeight()
+			let penultimateBlockHash = try await rpcInterface.getBlockHashHex(height: chaintip - 1)
+			try await rpcInterface.unmineBlock(hash: penultimateBlockHash)
+			try await rpcInterface.mineBlocks(number: 1, coinbaseDestinationAddress: testAddress)
+
+			try await rpcInterface.reconcileChaintips()
+			XCTAssertEqual(listener.newBlocksDetected, 3)
+			XCTAssertEqual(listener.blocksLost, 2)
+		}
+
+		do {
+			let testAddress = try await rpcInterface.generateAddress()
+			let chaintipHash = try await rpcInterface.getChaintipHashHex()
+			try await rpcInterface.unmineBlock(hash: chaintipHash)
+			try await rpcInterface.mineBlocks(number: 2, coinbaseDestinationAddress: testAddress)
+
+			try await rpcInterface.reconcileChaintips()
+			XCTAssertEqual(listener.newBlocksDetected, 5)
+			XCTAssertEqual(listener.blocksLost, 3)
+		}
 	}
 
 }