From 642d8cbe4b7883ef5d52738d0c2661ff8d67e61d Mon Sep 17 00:00:00 2001
From: myk002 <myk002@yahoo.com>
Date: Mon, 5 Apr 2021 01:37:43 -0700
Subject: [PATCH] handle nil values sent to printerr

---
 ci/test.lua                            |  1 +
 library/lua/test_util/expect.lua       |  2 +-
 test/library/test_util/expect_unit.lua | 39 +++++++++++++++++---------
 3 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/ci/test.lua b/ci/test.lua
index 956ce07b6..2209f58b8 100644
--- a/ci/test.lua
+++ b/ci/test.lua
@@ -270,6 +270,7 @@ local function detect_printerr(func)
     local saved_printerr = dfhack.printerr
     local printerr_called = false
     dfhack.printerr = function(msg)
+            if msg == nil then return end
             saved_printerr(msg)
             printerr_called = true
         end
diff --git a/library/lua/test_util/expect.lua b/library/lua/test_util/expect.lua
index 7ae1385c9..deca8c44f 100644
--- a/library/lua/test_util/expect.lua
+++ b/library/lua/test_util/expect.lua
@@ -164,7 +164,7 @@ function expect.printerr_match(matcher, func, comment)
         function() dfhack.printerr = saved_printerr end,
         func)
     if type(matcher) ~= 'table' then matcher = {matcher} end
-    while messages[1] do
+    while #messages > 0 do
         local msg = messages[1]
         if matches(msg, matcher[1]) then
             table.remove(matcher, 1)
diff --git a/test/library/test_util/expect_unit.lua b/test/library/test_util/expect_unit.lua
index 6094149fb..6c71b59c1 100644
--- a/test/library/test_util/expect_unit.lua
+++ b/test/library/test_util/expect_unit.lua
@@ -59,20 +59,6 @@ function test.printerr_match()
     local oneprint = function()
         dfhack.printerr('a')
     end
-    local twoprint = function()
-        dfhack.printerr('a')
-        dfhack.printerr('b')
-    end
-    local threeprint = function()
-        dfhack.printerr('a')
-        dfhack.printerr('b')
-        dfhack.printerr('c')
-    end
-    local multiprint = function()
-        dfhack.printerr('a')
-        dfhack.printerr('b')
-        dfhack.printerr('a')
-    end
 
     expect.true_(expect_raw.printerr_match(nil, noprint))
     expect.true_(expect_raw.printerr_match({}, noprint))
@@ -90,6 +76,10 @@ function test.printerr_match()
     expect.false_(expect_raw.printerr_match({b=1}, oneprint))
     expect.false_(expect_raw.printerr_match({a=1,b=1}, oneprint))
 
+    local twoprint = function()
+        dfhack.printerr('a')
+        dfhack.printerr('b')
+    end
     expect.true_(expect_raw.printerr_match({'a','b'}, twoprint))
     expect.true_(expect_raw.printerr_match({a=1,b=1}, twoprint))
     expect.false_(expect_raw.printerr_match({'b','a'}, twoprint))
@@ -98,8 +88,29 @@ function test.printerr_match()
     expect.false_(expect_raw.printerr_match({a=1,b=2}, twoprint))
     expect.false_(expect_raw.printerr_match({a=1,b=1,c=1}, twoprint))
 
+    local threeprint = function()
+        dfhack.printerr('a')
+        dfhack.printerr('b')
+        dfhack.printerr('c')
+    end
     expect.true_(expect_raw.printerr_match({a=1,b=1,c=1}, threeprint))
 
+    local multiprint = function()
+        dfhack.printerr('a')
+        dfhack.printerr('b')
+        dfhack.printerr('a')
+    end
     expect.true_(expect_raw.printerr_match({a=2,b=1}, multiprint))
     expect.false_(expect_raw.printerr_match({a=1,b=1}, multiprint))
+
+    local nilprint = function()
+        dfhack.printerr()
+    end
+    expect.true_(expect_raw.printerr_match({}, nilprint))
+
+    local nilaprint = function()
+        dfhack.printerr()
+        dfhack.printerr('a')
+    end
+    expect.true_(expect_raw.printerr_match({'a'}, nilaprint))
 end