multi: update blockchain and mempool error types.

This updates the blockchain and mempool error types to
leverage go 1.13 errors.Is/As functionality as well as confirm to
the error infrastructure best practices.

blockchain/chain.go

@@ -1260,21 +1260,22 @@ func (b *BlockChain) forceHeadReorganization(formerBest chainhash.Hash, newBest
 	// We can't reorganize the chain unless our head block matches up with
 	// b.bestChain.
 	if !formerBestNode.hash.IsEqual(&formerBest) {
-		return ruleError(ErrForceReorgWrongChain, "tried to force reorg "+
-			"on wrong chain")
+		str := "tried to force reorg on wrong chain"
+		return ruleError(ErrForceReorgWrongChain, str)
 	}
 
 	// Child to reorganize to is missing.
 	newBestNode := b.index.LookupNode(&newBest)
 	if newBestNode == nil || newBestNode.parent != formerBestNode.parent {
-		return ruleError(ErrForceReorgMissingChild, "missing child of "+
-			"common parent for forced reorg")
+		str := "missing child of common parent for forced reorg"
+		return ruleError(ErrForceReorgMissingChild, str)
 	}
 
 	// Don't allow a reorganize to a known invalid chain.
 	newBestNodeStatus := b.index.NodeStatus(newBestNode)
 	if newBestNodeStatus.KnownInvalid() {
-		return ruleError(ErrKnownInvalidBlock, "block is known to be invalid")
+		str := "block is known to be invalid"
+		return ruleError(ErrKnownInvalidBlock, str)
 	}
 
 	// Reorganize the chain and flush any potential unsaved changes to the

blockchain/chain_test.go

@@ -157,8 +157,8 @@ func TestForceHeadReorg(t *testing.T) {
 	//
 	// rejectForceTipReorg forces the chain instance to reorganize the
 	// current tip of the main chain from the given block to the given
-	// block and expected it to be rejected with the provided error code.
-	rejectForceTipReorg := func(fromTipName, toTipName string, code ErrorCode) {
+	// block and expected it to be rejected with the provided error kind.
+	rejectForceTipReorg := func(fromTipName, toTipName string, kind ErrorKind) {
 		from := g.BlockByName(fromTipName)
 		to := g.BlockByName(toTipName)
 		t.Logf("Testing forced reorg from %s (hash %s, height %d) "+
@@ -175,25 +175,15 @@ func TestForceHeadReorg(t *testing.T) {
 				to.Header.Height)
 		}
 
-		// Ensure the error code is of the expected type and the reject
-		// code matches the value specified in the test instance.
-		var rerr RuleError
-		if !errors.As(err, &rerr) {
-			t.Fatalf("forced header reorg from block %q (hash %s, "+
-				"height %d) to block %q (hash %s, height %d) "+
-				"returned unexpected error type -- got %T, "+
-				"want blockchain.RuleError", fromTipName,
-				from.BlockHash(), from.Header.Height, toTipName,
-				to.BlockHash(), to.Header.Height, err)
-		}
-		if rerr.ErrorCode != code {
+		// Ensure the error kind is of the expected type and matches
+		// the value specified in the test instance.
+		if !errors.Is(err, kind) {
 			t.Fatalf("forced header reorg from block %q (hash %s, "+
 				"height %d) to block %q (hash %s, height %d) "+
 				"does not have expected reject code -- got %v, "+
 				"want %v", fromTipName,
 				from.BlockHash(), from.Header.Height, toTipName,
-				to.BlockHash(), to.Header.Height, rerr.ErrorCode,
-				code)
+				to.BlockHash(), to.Header.Height, err, kind)
 		}
 	}
 

blockchain/common_test.go

@@ -532,8 +532,8 @@ func (g *chaingenHarness) AcceptTipBlock() {
 }
 
 // RejectBlock expects the block associated with the given name in the harness
-// generator to be rejected with the provided error code.
-func (g *chaingenHarness) RejectBlock(blockName string, code ErrorCode) {
+// generator to be rejected with the provided error kind.
+func (g *chaingenHarness) RejectBlock(blockName string, kind ErrorKind) {
 	g.t.Helper()
 
 	msgBlock := g.BlockByName(blockName)
@@ -548,27 +548,21 @@ func (g *chaingenHarness) RejectBlock(blockName string, code ErrorCode) {
 			blockName, block.Hash(), blockHeight)
 	}
 
-	// Ensure the error code is of the expected type and the reject code matches
+	// Ensure the error kind is of the expected type and matches
 	// the value specified in the test instance.
-	var rerr RuleError
-	if !errors.As(err, &rerr) {
-		g.t.Fatalf("block %q (hash %s, height %d) returned unexpected error "+
-			"type -- got %T, want blockchain.RuleError", blockName,
-			block.Hash(), blockHeight, err)
-	}
-	if rerr.ErrorCode != code {
+	if !errors.Is(err, kind) {
 		g.t.Fatalf("block %q (hash %s, height %d) does not have expected reject "+
 			"code -- got %v, want %v", blockName, block.Hash(), blockHeight,
-			rerr.ErrorCode, code)
+			err, kind)
 	}
 }
 
 // RejectTipBlock expects the current tip block associated with the harness
 // generator to be rejected with the provided error code.
-func (g *chaingenHarness) RejectTipBlock(code ErrorCode) {
+func (g *chaingenHarness) RejectTipBlock(kind ErrorKind) {
 	g.t.Helper()
 
-	g.RejectBlock(g.TipName(), code)
+	g.RejectBlock(g.TipName(), kind)
 }
 
 // ExpectTip expects the provided block to be the current tip of the main chain