A couple of io fixes

- Use expect within io.write before calling the handle's write
   function. Closes #338
 - Coerce to string in write before doing any writing. Fixes #339

src/main/resources/assets/computercraft/lua/bios.lua

@@ -207,6 +207,7 @@ function write( sText )
     end
 
     -- Print the line with proper word wrapping
+    sText = tostring(sText)
     while #sText > 0 do
         local whitespace = string.match( sText, "^[ \t]+" )
         if whitespace then

src/main/resources/assets/computercraft/lua/rom/apis/io.lua

@@ -122,7 +122,11 @@ handleMetatable = {
             if not handle.write then return nil, "file is not writable" end
 
             local n = select("#", ...)
-            for i = 1, n do handle.write(select(i, ...)) end
+            for i = 1, n do
+                local arg = select(i, ...)
+                expect(1, arg, "string", "number")
+                handle.write(arg)
+            end
             return self
         end,
     },

src/test/resources/test-rom/spec/base_spec.lua

@@ -1,3 +1,5 @@
+local with_window = require "test_helpers".with_window
+
 describe("The Lua base library", function()
     describe("sleep", function()
         it("validates arguments", function()
@@ -13,6 +15,16 @@ describe("The Lua base library", function()
             write("")
             expect.error(write, nil):eq("bad argument #1 (expected string or number, got nil)")
         end)
+
+        it("writes numbers", function()
+            local w = with_window(5, 5, function() write(123) end)
+            expect(w.getLine(1)):eq("123  ")
+        end)
+
+        it("writes strings", function()
+            local w = with_window(5, 5, function() write("abc") end)
+            expect(w.getLine(1)):eq("abc  ")
+        end)
     end)
 
     describe("loadfile", function()

src/test/resources/test-rom/spec/test_helpers.lua

@@ -41,6 +41,22 @@ local function capture_program(stub, program, ...)
     }
 end
 
+--- Run a function redirecting to a new window with the given dimensions
+--
+-- @tparam number width The window's width
+-- @tparam number height The window's height
+-- @tparam function() fn The action to run
+-- @treturn window.Window The window, whose content can be queried.
+local function with_window(width, height, fn)
+    local current = term.current()
+    local redirect = window.create(current, 1, 1, width, height, false)
+    term.redirect(redirect)
+    fn()
+    term.redirect(current)
+    return redirect
+end
+
 return {
     capture_program = capture_program,
+    with_window = with_window,
 }