featureflags: fix a bug which caused all flags to report as 'false' (#268)

- Adds the featureflag unit test, which was missing from my previous PR (forgot to add).
 - Adds a set of special internal values to help verify the behavior of the three possible valid macro states.
 - Also clarifies the use of "feature flags" as the term for this new table, both in function name and comments.

Author: jstine35

lutro.c

@@ -204,28 +204,38 @@ static void init_lutro_global_table(lua_State *L)
    lua_pop(L, 1);
 }
 
-// reveals which configuration options were used to compile lutro.
-static void init_config(lua_State *L)
+// exposes  build configuration options used to compile lutro to lua
+static void init_feature_flags(lua_State *L)
 {   
    player_checked_stack_begin(L);
 
    luax_reqglobal(L, "lutro");
    lua_newtable(L);
 
-   char buf[128];
+   char buf[64];
 
-   #define STR(a) #a
-   #define CAPABILITY(cap)                           \
-      snprintf(buf, sizeof(buf), "%s", #cap);        \
-      lua_pushboolean(L, (buf[0] && strtold(buf, NULL) != 0)); \
-      lua_setfield(L, -2, #cap)
+   #define _CAPABILITY(capname, capval) \
+      snprintf(buf, sizeof(buf), "%s", # capval);     \
+      lua_pushboolean(L, (buf[0] && strtod(buf, NULL) != 0)); \
+      lua_setfield(L, -2, capname)
+
+   #define CAPABILITY(cap) _CAPABILITY(#cap, cap)
 
    CAPABILITY(HAVE_COMPOSITION);
    CAPABILITY(HAVE_TRANSFORM);
    CAPABILITY(HAVE_INOTIFY);
    CAPABILITY(HAVE_JIT);
    CAPABILITY(HAVE_LUASOCKET);
 
+   // for unit testing purposes only.
+   #define _VERIFY_AS_TRUE  1
+   #define _VERIFY_AS_FALSE 0
+   CAPABILITY(_VERIFY_AS_TRUE);
+   CAPABILITY(_VERIFY_AS_FALSE);
+   CAPABILITY(_VERIFY_AS_UNDEFINED);
+   #undef _VERIFY_AS_TRUE
+   #undef _VERIFY_AS_FALSE
+
    #undef STR
    #undef CAPABILITY
 
@@ -237,7 +247,7 @@ static void init_config(lua_State *L)
 
 static int lutro_core_preload(lua_State *L)
 {
-   init_config(L);
+   init_feature_flags(L);
 
    return 1;
 }

test/main.lua

@@ -1,6 +1,5 @@
 -- Lutro Tester
 local availableStates = {
-	"config/print",
 	"graphics/print",
 	"unit/tests",
 	"joystick/isDown",

test/unit/modules/featureflags.lua

@@ -0,0 +1,37 @@
+
+local function printBuildFlags()
+    -- Step 1: duplicate the table
+    -- Step 2: Sort the array alphabetically
+    -- Step 3: Iterate over the sorted array
+
+    local copy = {}
+    for k in pairs(lutro.featureflags) do
+        table.insert(copy, k)
+    end
+
+    table.sort(copy, function(a, b)
+        return a:lower() < b:lower()
+    end)
+
+    -- named prefixed with _ are for internal lutro use.
+    for _, key in ipairs(copy) do
+        if not key:find("^_") then
+            print( ("lutro.featureflags.%s = %s"):format(key, tostring(lutro.featureflags[key])) )
+        end
+    end
+end
+
+local function verify_as_truefalse()
+    unit.assertEquals(lutro.featureflags._VERIFY_AS_TRUE,  true)
+    unit.assertEquals(lutro.featureflags._VERIFY_AS_FALSE, false)
+end
+
+local function verify_as_undefined()
+    unit.assertEquals(lutro.featureflags._VERIFY_AS_UNDEFINED, false)
+end
+
+return {
+    printBuildFlags,
+    verify_as_truefalse,
+    verify_as_undefined,
+}