.

wcfs/internal/xbtree/δbtail_test.go

@@ -19,7 +19,29 @@
 
 package xbtree
 // tests for δbtail.go
-// XXX doc  (2 ways of testing: explicit + allstructs), treegen py helper
+//
+// This are the main tests for ΔBtail functionality. There are two primary testing concerns:
+//
+//   1) to verify treediff algorithm, and
+//   2) to verify how ΔTtail rebuilds its history entries when set of tracked keys
+//      grow upon either new Track requests, or upon Update that turned out to
+//      trigger such growth of set of tracked keys.
+//
+// TestΔBTail*/Update and TestΔBTail*/rebuild exercise points "1" and "2" correspondingly.
+//
+// There are 2 testing approaches:
+//
+//   a) transition a BTree in ZODB through particular tricky tree topologies
+//      and feed ΔBtail through created database transactions.
+//   b) transition a BTree in ZODB through random tree topologies and feed
+//      ΔBtail through created database transactions.
+//
+// TestΔBTail and TestΔBTailAllStructs implement approaches "a" and "b" correspondingly.
+//
+// testprog/treegen.py is used as helper to both:
+//
+//   - commit a particular BTree topology into ZODB, and
+//   - to generate set of random tree topologies that all correspond to particular {k->v} dict.
 
 import (
 	"bufio"
@@ -47,8 +69,6 @@ import (
 	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xzodb"
 )
 
-// XXX move infrastructure -> δbtail_treegen_test.go ?
-
 // TreeGenSrv represents connection to running `treegen ...` server.
 type TreeGenSrv struct {
 	argv      []string