gdiplus/tests: Add parameter validation test for GdipGetFontCollectionFamilyCount().

dlls/gdiplus/tests/font.c

@@ -1238,6 +1238,27 @@ static void test_GdipGetFontCollectionFamilyList(void)
     GdipDeleteFontFamily(family2);
 }
 
+static void test_GdipGetFontCollectionFamilyCount(void)
+{
+    GpFontCollection *collection;
+    GpStatus status;
+    INT count;
+
+    status = GdipGetFontCollectionFamilyCount(NULL, NULL);
+    ok(status == InvalidParameter, "Unexpected status %d.\n", status);
+
+    count = 123;
+    status = GdipGetFontCollectionFamilyCount(NULL, &count);
+    ok(status == InvalidParameter, "Unexpected status %d.\n", status);
+    ok(count == 123, "Unexpected family count %d.\n", count);
+
+    status = GdipNewInstalledFontCollection(&collection);
+    ok(status == Ok, "Failed to get system collection, status %d.\n", status);
+
+    status = GdipGetFontCollectionFamilyCount(collection, NULL);
+    ok(status == InvalidParameter, "Unexpected status %d.\n", status);
+}
+
 START_TEST(font)
 {
     struct GdiplusStartupInput gdiplusStartupInput;
@@ -1269,6 +1290,7 @@ START_TEST(font)
     test_installedfonts();
     test_heightgivendpi();
     test_GdipGetFontCollectionFamilyList();
+    test_GdipGetFontCollectionFamilyCount();
 
     GdiplusShutdown(gdiplusToken);
 }