pp: implement verbose serialization of box errors

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Implemented verbose serialization of uncaught box errors thrown in tests
+  (gh-445).
 - Fixed a bug when errors reported by the address sanitizer during process
   termination were ignored (gh-460).
 

luatest/assertions.lua

@@ -13,7 +13,6 @@ local log = require('luatest.log')
 local utils = require('luatest.utils')
 local tarantool = require('tarantool')
 local fio = require('fio')
-local ffi = require('ffi')
 
 local prettystr = pp.tostring
 local prettystr_pairs = pp.tostring_pair
@@ -22,8 +21,6 @@ local M = {}
 
 local xfail = false
 
-local box_error_type = ffi.typeof(box.error.new(box.error.UNKNOWN))
-
 -- private exported functions (for testing)
 M.private = {}
 
@@ -159,7 +156,7 @@ local function pcall_check_trace(level, fn, ...)
     if ok then
         return ok, err
     end
-    if type(err) ~= 'cdata' or ffi.typeof(err) ~= box_error_type then
+    if not utils.is_box_error(err) then
         fail_fmt(level + 1, nil, 'Error raised is not a box.error: %s',
                  prettystr(err))
     end
@@ -704,21 +701,6 @@ function M.assert_error_msg_matches(pattern, fn, ...)
     end
 end
 
--- If it is box.error that unpack it recursively. If it is not then
--- return argument unchanged.
-local function error_unpack(err)
-    if type(err) ~= 'cdata' or ffi.typeof(err) ~= box_error_type then
-        return err
-    end
-    local unpacked = err:unpack()
-    local tmp = unpacked
-    while tmp.prev ~= nil do
-        tmp.prev = tmp.prev:unpack()
-        tmp = tmp.prev
-    end
-    return unpacked
-end
-
 --- Checks that error raised by function is table that includes expected one.
 --- box.error is unpacked to convert to table. Stacked errors are supported.
 --- That is if there is prev field in expected then it should cover prev field
@@ -734,7 +716,7 @@ function M.assert_error_covers(expected, fn, ...)
                  'Function successfully returned: %s\nExpected error: %s',
                   prettystr(actual), prettystr(expected))
     end
-    local unpacked = error_unpack(actual)
+    local unpacked = utils.error_unpack(actual)
     if not comparator.equals(table_slice(unpacked, expected), expected) then
         actual, expected = prettystr_pairs(unpacked, expected)
         fail_fmt(2, nil, 'Error expected: %s\nError received: %s',

luatest/pp.lua

@@ -1,5 +1,6 @@
 local Class = require('luatest.class')
 local sorted_pairs = require('luatest.sorted_pairs')
+local utils = require('luatest.utils')
 
 -- Pretty printer.
 local pp = {
@@ -160,6 +161,8 @@ function Formatter.mt:format(v, indentLevel)
                 return tostring(i)
             end
         end
+    elseif utils.is_box_error(v) then
+        return self:format_table(utils.error_unpack(v), indentLevel)
     end
 
     return tostring(v)

luatest/utils.lua

@@ -1,10 +1,13 @@
 local digest = require('digest')
+local ffi = require('ffi')
 local fio = require('fio')
 local fun = require('fun')
 local yaml = require('yaml')
 
 local utils = {}
 
+local box_error_type = ffi.typeof(box.error.new(box.error.UNKNOWN))
+
 -- Helper to override methods.
 --
 --     utils.patch(target, 'method_name', function(super) return function(...)
@@ -251,4 +254,23 @@ function utils.table_is_array(t)
     return true
 end
 
+function utils.is_box_error(err)
+    return type(err) == 'cdata' and ffi.typeof(err) == box_error_type
+end
+
+-- If it is box.error that unpack it recursively. If it is not then
+-- return argument unchanged.
+function utils.error_unpack(err)
+    if not utils.is_box_error(err) then
+        return err
+    end
+    local unpacked = err:unpack()
+    local tmp = unpacked
+    while tmp.prev ~= nil do
+        tmp.prev = tmp.prev:unpack()
+        tmp = tmp.prev
+    end
+    return unpacked
+end
+
 return utils

test/pp_test.lua

@@ -31,3 +31,11 @@ g.test_tostring_huge_table = function()
     t.assert_equals(result, 0)
     t.assert_almost_equals(clock.time() - start, 0, 0.5)
 end
+
+g.test_tostring_box_error = function()
+    local s = pp.tostring(box.error.new({
+        type = 'MyError', reason = 'FOOBAR',
+    }))
+    t.assert_str_contains(s, 'type = "MyError"')
+    t.assert_str_contains(s, 'message = "FOOBAR"')
+end

test/utils_test.lua

@@ -30,3 +30,16 @@ g.test_table_pack = function()
     t.assert_equals(utils.table_pack(1, 2, nil), {n = 3, 1, 2})
     t.assert_equals(utils.table_pack(1, 2, nil, 3), {n = 4, 1, 2, nil, 3})
 end
+
+g.test_box_error = function()
+    local err = 'FOOBAR'
+    t.assert_not(utils.is_box_error(err))
+    t.assert_equals(utils.error_unpack(err), err)
+    err = box.error.new({type = 'MyError', reason = 'FOOBAR'})
+    err:set_prev(box.error.new({type = 'MyError2', reason = 'FUZZ'}))
+    t.assert(utils.is_box_error(err))
+    t.assert_covers(utils.error_unpack(err), {
+        type = 'MyError', message = 'FOOBAR',
+        prev = {type = 'MyError2', message = 'FUZZ'}
+    })
+end