tools.test: print the callstack in test failures

So when mason reports a test failure it should include the whole
callstack. That should make it easier to catch the "No suitable
arithmetic method" random error that is hard to debug without a
callstack.

basis/debugger/debugger-tests.factor

@@ -1,4 +1,4 @@
-USING: accessors alien.syntax continuations debugger kernel
+USING: accessors alien.syntax continuations debugger kernel literals
 namespaces tools.test ;
 IN: debugger.tests
 
@@ -36,7 +36,7 @@ T{ test-failure
        { asset { "Unit Test" [ ] [ dup ] } }
        { path "resource:basis/game/input/input-tests.factor" }
        { line# 6 }
-    { continuation f }
+       { continuation $[ current-continuation ] }
     } error.
 ] unit-test
 

basis/tools/test/test-tests.factor

@@ -1,8 +1,20 @@
 IN: tools.test.tests
-USING: tools.test tools.test.private namespaces kernel sequences ;
+USING: continuations debugger io.streams.string kernel namespaces
+sequences tools.test tools.test.private ;
 
 { 1 } [
     [
         [ "OOPS" ] must-fail
     ] fake-unit-test length
 ] unit-test
+
+: create-test-failure ( -- error )
+    [ "hello" throw ] [
+        f "path" 25 error-continuation get test-failure boa
+    ] recover ;
+
+! Just verifies that the presented output contains a callstack.
+{ t } [
+    create-test-failure [ error. ] with-string-writer
+    "OBJ-CURRENT-THREAD" swap subseq?
+] unit-test

basis/tools/test/test.factor

@@ -161,7 +161,7 @@ M: test-failure error. ( error -- )
         [ error-location print nl ]
         [ asset>> [ experiment. nl ] when* ]
         [ error>> error. ]
-        [ continuation>> traceback-link. ]
+        [ continuation>> call>> callstack. ]
     } cleave ;
 
 : :test-failures ( -- ) test-failures get errors. ;