oleaut32: Added some SysFreeString tests.

dlls/oleaut32/tests/vartype.c

@@ -6072,6 +6072,47 @@ static void test_ChangeType_keep_dst(void)
      SysFreeString(bstr);
 }
 
+/* This tests assumes an empty cache, so it needs to be ran early in the test. */
+static void test_bstr_cache(void)
+{
+    BSTR str, str2, strs[20];
+    unsigned i;
+
+    static const WCHAR testW[] = {'t','e','s','t',0};
+
+    str = SysAllocString(testW);
+    /* This should put the string into cache */
+    SysFreeString(str);
+    /* The string is in cache, this won't touch it */
+    SysFreeString(str);
+
+    ok(SysStringLen(str) == 4, "unexpected len\n");
+    ok(!lstrcmpW(str, testW), "string changed\n");
+
+    str2 = SysAllocString(testW);
+    ok(str == str2, "str != str2\n");
+    SysFreeString(str2);
+
+    /* Fill the bucket with cached entries. */
+    for(i=0; i < sizeof(strs)/sizeof(*strs); i++)
+        strs[i] = SysAllocStringLen(NULL, 24);
+    for(i=0; i < sizeof(strs)/sizeof(*strs); i++)
+        SysFreeString(strs[i]);
+
+    /* Following allocation will be made from cache */
+    str = SysAllocStringLen(NULL, 24);
+    ok(str == strs[0], "str != strs[0]\n");
+
+    /* Smaller buffers may also use larget cached buffers */
+    str2 = SysAllocStringLen(NULL, 16);
+    ok(str2 == strs[1], "str2 != strs[1]\n");
+
+    SysFreeString(str);
+    SysFreeString(str2);
+    SysFreeString(str);
+    SysFreeString(str2);
+}
+
 START_TEST(vartype)
 {
   hOleaut32 = GetModuleHandleA("oleaut32.dll");
@@ -6079,6 +6120,8 @@ START_TEST(vartype)
   trace("LCIDs: System=0x%08x, User=0x%08x\n", GetSystemDefaultLCID(),
         GetUserDefaultLCID());
 
+  test_bstr_cache();
+
   test_VarI1FromI2();
   test_VarI1FromI4();
   test_VarI1FromI8();