add a unit test for add/free prefixes. fix bad free_prefixes call site.

src/kernel/config.c

@@ -1768,7 +1768,6 @@ void free_gamedata(void)
     free_units();
     free_regions();
     free_borders();
-    free_prefixes();
 
     for (i = 0; i != MAXLOCALES; ++i) {
         if (defaults[i]) {

src/laws.c

@@ -1469,7 +1469,7 @@ static void init_prefixnames(void)
         in->next = pnames;
         in->lang = lang;
 
-        if (!exist) {
+        if (!exist && race_prefixes) {
             int key;
             for (key = 0; race_prefixes[key]; ++key) {
                 variant var;

src/prefix.test.c

@@ -1,9 +1,29 @@
 #include "prefix.h"
 
+#include <tests.h>
+
+#include <stddef.h>
 #include <CuTest.h>
 
+static void test_add_prefix(CuTest *tc) {
+    test_cleanup();
+    CuAssertPtrEquals(tc, 0, race_prefixes);
+    add_raceprefix("sea");
+    CuAssertPtrNotNull(tc, race_prefixes);
+    CuAssertStrEquals(tc, "sea", race_prefixes[0]);
+    CuAssertPtrEquals(tc, 0, race_prefixes[1]);
+    add_raceprefix("moon");
+    CuAssertStrEquals(tc, "sea", race_prefixes[0]);
+    CuAssertStrEquals(tc, "moon", race_prefixes[1]);
+    CuAssertPtrEquals(tc, 0, race_prefixes[2]);
+    free_prefixes();
+    CuAssertPtrEquals(tc, 0, race_prefixes);
+    test_cleanup();
+}
+
 CuSuite *get_prefix_suite(void)
 {
     CuSuite *suite = CuSuiteNew();
+    SUITE_ADD_TEST(suite, test_add_prefix);
     return suite;
 }

src/tests.c

@@ -2,6 +2,7 @@
 #include "tests.h"
 #include "keyword.h"
 #include "seen.h"
+#include "prefix.h"
 
 #include <kernel/config.h>
 #include <kernel/region.h>
@@ -84,6 +85,7 @@ void test_cleanup(void)
     free_spellbooks();
     free_gamedata();
     free_seen();
+    free_prefixes();
     mt_clear();
     if (!mt_find("missing_message")) {
         mt_register(mt_new_va("missing_message", "name:string", 0));