error on unmatched printerr output during a test

- provides expect,printerr_match for matching printerr output
- fails tests if printerr is called outside the printerr_match wrapper
- changes api of expect.error_match to mirror the new printerr_match api

ci/test.lua

@@ -141,6 +141,49 @@ local function load_test_config(config_file)
     return config
 end
 
+local function run_expect_func(func, ...)
+    local args = {...}
+    local saved_printerr = dfhack.printerr
+    local printerr_called = false
+    dfhack.printerr = function(msg) printerr_called = true end
+    return dfhack.with_finalize(
+        function() dfhack.printerr = saved_printerr end,
+        function()
+            local ret = {func(table.unpack(args))}
+            if printerr_called then
+                return {false,
+                        "dfhack.printerr was called outside of" ..
+                        " expect.printerr_match(). please wrap your test" ..
+                        " with expect.printerr_match()."}
+            end
+            return ret
+        end
+    )
+end
+
+local function wrap_expect(func, private)
+    return function(...)
+        private.checks = private.checks + 1
+        local ret = run_expect_func(func, ...)
+        local ok = table.remove(ret, 1)
+        if ok then
+            private.checks_ok = private.checks_ok + 1
+            return
+        end
+        local msg = ''
+        for _, part in pairs(ret) do
+            if part then
+                msg = msg .. ': ' .. tostring(part)
+            end
+        end
+        msg = msg:sub(3) -- strip leading ': '
+        dfhack.printerr('Check failed! ' .. (msg or '(no message)'))
+        local info = debug.getinfo(2)
+        dfhack.printerr(('  at %s:%d'):format(info.short_src, info.currentline))
+        print('')
+    end
+end
+
 local function build_test_env()
     local env = {
         test = utils.OrderedTable(),
@@ -157,26 +200,7 @@ local function build_test_env()
         checks_ok = 0,
     }
     for name, func in pairs(expect) do
-        env.expect[name] = function(...)
+        env.expect[name] = wrap_expect(func, private)
-            private.checks = private.checks + 1
-            local ret = {func(...)}
-            local ok = table.remove(ret, 1)
-            local msg = ''
-            for _, part in pairs(ret) do
-                if part then
-                    msg = msg .. ': ' .. tostring(part)
-                end
-            end
-            msg = msg:sub(3) -- strip leading ': '
-            if ok then
-                private.checks_ok = private.checks_ok + 1
-            else
-                dfhack.printerr('Check failed! ' .. (msg or '(no message)'))
-                local info = debug.getinfo(2)
-                dfhack.printerr(('  at %s:%d'):format(info.short_src, info.currentline))
-                print('')
-            end
-        end
     end
     setmetatable(env, {__index = _G})
     return env, private

library/lua/test/expect.lua

@@ -101,25 +101,130 @@ function expect.table_eq(a, b, comment)
             ('key %s: "%s" ~= "%s"'):format(keystr, diff[1], diff[2])
 end
 
-function expect.error(func, ...)
+function expect.error(func, comment)
-    local ok, ret = pcall(func, ...)
+    local ok = pcall(func)
     if ok then
-        return false, 'no error raised by function call'
+        return false, comment, 'no error raised by function call'
     else
         return true
     end
 end
 
-function expect.error_match(func, matcher, ...)
+local function matches(obj, matcher)
-    local ok, err = pcall(func, ...)
+    if not matcher then return false end
-    if ok then
+    if type(matcher) == 'boolean' then
-        return false, 'no error raised by function call'
+        return true
     elseif type(matcher) == 'string' then
-        if not tostring(err):match(matcher) then
+        return tostring(obj):match(matcher)
-            return false, ('error "%s" did not match "%s"'):format(err, matcher)
+    elseif type(matcher) == 'function' then
+        return matcher(obj)
+    end
+    return false
+end
+
+-- matches errors thrown from the specified function. the check passes if an
+-- error is thrown and the thrown error matches the specified matcher.
+--
+-- matcher can be:
+--  a string, interpreted as a lua pattern that matches the error message
+--  a function that takes an err object and returns a boolean (true means match)
+--  the literal value true, which matches any thrown error
+function expect.error_match(matcher, func, comment)
+    local ok, err = pcall(func)
+    if ok then
+        return false, comment, 'no error raised by function call'
+    end
+    if matches(err, matcher) then return true end
+    local matcher_str = ''
+    if type(matcher) == 'string' then
+        matcher_str = (': "%s"'):format(matcher)
+    end
+    return false,
+            ('error "%s" did not satisfy matcher%s'):format(err, matcher_str)
+end
+
+-- matches error messages output from dfhack.printerr() when the specified
+-- callback is run. the check passes if all printerr messages are matched by
+-- specified matchers and no matchers remain unmatched.
+--
+-- matcher can be:
+--  a string, interpreted as a lua pattern that matches a message
+--  a function that takes the string message and returns a boolean (true means
+--    match)
+--  the literal value true, which matches any message
+--  the literal value false, nil, or an empty table, which match the absence of
+--    printerr messages
+--  a populated table that can be used to match multiple messages (explained
+--    in more detail below)
+--
+-- if matcher is a table, it can contain:
+--  a list of strings, literal true values, and/or functions which will be
+--    matched in order
+--  a map of strings, literal true values, and/or functions to positive
+--    integers, which will be matched (in any order) the number of times
+--    specified
+--
+-- when this function attempts to match a message, it will first try the next
+-- matcher in the list (that is, the next numeric key). if that matcher doesn't
+-- exist or doesn't match, it will try all string and function keys whose values
+-- are numeric and > 0. if none of those match, it will check for a key equal to
+-- true with a value > 0.
+--
+-- if a mapped matcher is matched, it will have its value decremented by 1.
+function expect.printerr_match(matcher, func, comment)
+    local saved_printerr = dfhack.printerr
+    local messages = {}
+    dfhack.printerr = function(msg) table.insert(messages, msg) end
+    dfhack.with_finalize(
+        function() dfhack.printerr = saved_printerr end,
+        func)
+    if not matcher then
+        local num_messages = #messages
+        if num_messages == 0 then return true end
+        return false, comment, ('expected 0 calls to dfhack.printerr but got' ..
+                                ' %d'):format(num_messages)
+    end
+    if type(matcher) ~= 'table' then matcher = {matcher} end
+    local true_count = matcher[true] or 0
+    matcher[true] = nil
+    for _,msg in ipairs(messages) do
+        local m = matcher[1]
+        if matches(msg, m) then
+            table.remove(matcher, 1)
+            goto continue
+        end
+        for k,v in pairs(matcher) do
+            if type(v) == 'number' and v > 0 and matches(msg, k) then
+                local remaining = v - 1
+                if v == 0 then
+                    matcher[k] = nil
+                else
+                    matcher[k] = remaining
+                end
+                goto continue
+            end
+        end
+        if true_count > 0 then
+            true_count = true_count - 1
+            goto continue
+        end
+        return false, comment, ('unmatched printerr message: "%s"'):format(msg)
+        ::continue::
+    end
+    local extra_matchers = {}
+    for k,v in ipairs(matcher) do
+        table.insert(extra_matchers, ('"%s"'):format(v))
+        matcher[k] = nil
+    end
+    for k,v in pairs(matcher) do
+        table.insert(extra_matchers, ('"%s"=%d'):format(k, v))
+    end
+    if true_count > 0 then
+        table.insert(extra_matchers, ('true=%d'):format(true_count))
     end
-    elseif not matcher(err) then
+    if #extra_matchers > 0 then
-        return false, ('error "%s" did not satisfy matcher'):format(err)
+        return false, comment, ('unmatched or invalid matchers: %s'):format(
+            table.concat(extra_matchers, ', '))
     end
     return true
 end