Backstab unit tests: check that backstab works in a free-for-all

The units on the outsides of a backstab don't have to be allied
to each other, they just have to be enemies of the victim. That's
hardcoded into the AI via attack.cpp's backstab_check() function,
hence a unit test to check that WEAPON_SPECIAL_BACKSTAB activates
in that situation.

Add a new map with 4 sides all on separate castles. This is a
variation of the generic 2p unit test map, extended in the south
with a horizontal reflection of existing map.

Add a MAP_FILE argument to COMMON_KEEP_A_B_C_D_UNIT_TEST,
because it's the same setup except for the map file.

data/test/macros/generic_backstab_test.cfg

@@ -18,7 +18,10 @@
     #
     # The unit on hex spawn_points[0] then attacks Bob, and the test asserts
     # that Bob has the expected number of hit points remaining.
-    {GENERIC_UNIT_TEST {NAME} (
+    #
+    # The map has 4 sides, none of the allied to each other, with the leaders
+    # of the other sides far enough away to not interfere with the test.
+    {COMMON_KEEP_A_B_C_D_UNIT_TEST {NAME} (
         [event]
             # Using this event instead of "start" because units get healed after "start", which makes debugging more confusing
             name=side 1 turn 1
@@ -98,5 +101,5 @@
 
             {SUCCEED}
         [/event]
-    )}
+    ) (MAP_FILE="data/test/maps/4p_separate_castles.map")}
 #enddef

data/test/macros/start_position_common_keep_a_b_c_d.cfg

@@ -8,18 +8,23 @@
 # Side 3 leader Charlie (Orcish Grunt)
 # Side 4 leader Dave (Orcish Grunt)
 #
-# All four leaders are on a single keep, with Alice and Bob already in position to attack any of the other units. None of the sides are allied.
+# None of the sides are allied.
 #
-# There is no free castle hex to recruit onto.
+# On the default map (used unless overridden with the MAP_FILE argument:
+# * All four leaders are on a single keep, with Alice and Bob already in position to attack any of the other units.
+# * There is no free castle hex to recruit onto.
 ##
 #define COMMON_KEEP_A_B_C_D_UNIT_TEST NAME CONTENT
 
 #arg SIDE_LEADER
 Orcish Grunt#endarg
 
+#arg MAP_FILE
+test/maps/4p_single_castle.map#endarg
+
     [test]
         name=_ "Unit Test " + {NAME}
-        map_file=test/maps/4p_single_castle.map
+        map_file={MAP_FILE}
         turns=unlimited
         id={NAME}
         random_start_time=no

data/test/maps/4p_separate_castles.map

@@ -0,0 +1,15 @@
+Gg, Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, 1 Kha^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, 2 Kha^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Cha^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Cha^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov
+Gg^Kov, Gg^Kov, Gg^Kov, Chs^Kov, Gg^Kov, Chs^Kov, Gg^Kov, Ch^Kov, Gg^Kov, Ch^Kov, Gg^Kov, Chs^Kov, Gg^Kov, Ch^Kov, Gg^Kov, Ch^Kov, Gg^Kov, Gg^Kov
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg
+Gg^Kov, Gg^Kov, Gg^Kov, left Chs^Kov, Gg^Kov, Chs^Kov, Gg^Kov, Ch^Kov, Gg^Kov, Ch^Kov, Gg^Kov, Chs^Kov, Gg^Kov, Ch^Kov, Gg^Kov, right Ch^Kov, Gg^Kov, Gg
+Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg, Gg^Kov, Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg, Gg
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Cha^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Cha^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, 3 Kha^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, 4 Kha^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov
+Gg, Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg, Gg^Kov, Gg^Kov, Gg^Kov, Gg
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov
+Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov, Gg^Kov

data/test/scenarios/wml_tests/UnitsWML/AbilitiesWML/backstab.cfg

@@ -70,3 +70,30 @@
         side=2
     [/modify_unit]
 )}
+
+#####
+# API(s) being tested: WEAPON_SPECIAL_BACKSTAB
+##
+# Actions:
+# Bob is made to have 0% defense and given 100 hp.
+# A Rogue is spawned north, south of Bob.
+# The south Rogue is an enemy of both Bob and of the attacker.
+# The north Rogue attacks Bob.
+##
+# Expected end state:
+# The damage shows that Bob was backstabbed.
+# Bob gets hit all three times and ends with 100-(6 * 3 * 2) hp.
+#####
+{GENERIC_BACKSTAB_TEST "backstab_active_with_free_for_all" "n,s" yes (
+    # Although the core weapon special is implemented using WFL,
+    # the logic is also hardcoded into the via in attack.cpp's
+    # function backstab_check(). This test is a reminder to change
+    # the C++ if someone changes the WFL.
+    [modify_unit]
+        [filter]
+            x=$spawn_points[1].x
+            y=$spawn_points[1].y
+        [/filter]
+        side=3
+    [/modify_unit]
+)}

wml_test_schedule

@@ -346,6 +346,7 @@
 0 feeding_on_dead
 0 firststrike_and_laststrike
 0 backstab_active_with_accomplice_behind_bob
+0 backstab_active_with_free_for_all
 0 backstab_inactive_with_triangular_formation
 0 backstab_inactive_with_statue_behind_bob
 0 backstab_inactive_with_bobs_ally_behind_bob