.

wcfs/δbtail_test.go

@@ -691,6 +691,22 @@ type ΔBTestEntry struct {
 	kadjOK map[Key]SetKey // adjacency matrix against previous case
 }
 
+// ΔBTest converts xtest into ΔBTestEntry.
+// xtest can be string|ΔBTestEntry.
+func ΔBTest(xtest interface{}) ΔBTestEntry {
+	var test ΔBTestEntry
+	switch xtest := xtest.(type) {
+	case string:
+		test.tree   = xtest
+		test.kadjOK = nil
+	case ΔBTestEntry:
+		test = xtest
+	default:
+		panic(fmt.Sprintf("BUG: ΔBTest: bad type %T", xtest))
+	}
+	return test
+}
+
 // testΔBTail verifies ΔBTail on sequence of tree topologies coming from testq.
 func testΔBTail(t *testing.T, testq chan ΔBTestEntry) {
 	X := exc.Raiseif
@@ -881,25 +897,18 @@ func TestΔBTail(t *testing.T) {
 	}
 	// direct  tree_i -> tree_{i+1} -> _{i+2} ...   plus
 	// reverse ... tree_i <- _{i+1} <- _{i+2}
+	kadjOK := ΔBTest(testv[len(testv)-1]).kadjOK
 	for i := len(testv)-2; i >= 0; i-- {
-		testv = append(testv, testv[i])
+		test := ΔBTest(testv[i])
+		kadjOK, test.kadjOK = test.kadjOK, kadjOK
+		testv = append(testv, test)
 	}
 
 	testq := make(chan ΔBTestEntry)
 	go func() {
 		defer close(testq)
-		for _, xtest := range testv {
-			var test ΔBTestEntry
-			switch xtest := xtest.(type) {
-			case string:
-				test.tree   = xtest
-				test.kadjOK = nil
-			case ΔBTestEntry:
-				test = xtest
-			default:
-				panic(fmt.Sprintf("BUG: bad type in testv: %T", xtest))
-			}
-			testq <- test
+		for _, test := range testv {
+			testq <- ΔBTest(test)
 		}
 	}()
 	testΔBTail(t, testq)