Add: MockFontCache for testing GUI code that only needs to know font sizes.

src/fontcache.h

@@ -19,9 +19,8 @@ static const GlyphID SPRITE_GLYPH = 1U << 30;
 
 /** Font cache for basic fonts. */
 class FontCache {
-private:
-	static FontCache *caches[FS_END]; ///< All the font caches.
 protected:
+	static FontCache *caches[FS_END]; ///< All the font caches.
 	FontCache *parent;                ///< The parent of this font cache.
 	const FontSize fs;                ///< The size of the font.
 	int height;                       ///< The height of the font.

src/tests/CMakeLists.txt

@@ -1,6 +1,7 @@
 add_test_files(
     landscape_partial_pixel_z.cpp
     math_func.cpp
+    mock_fontcache.h
     string_func.cpp
     strings_func.cpp
     test_main.cpp

src/tests/mock_fontcache.h

@@ -0,0 +1,45 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file mock_fontcache.h Mock font cache implementation definition. */
+
+#ifndef MOCK_FONTCACHE_H
+#define MOCK_FONTCACHE_H
+
+#include "../stdafx.h"
+
+#include "../fontcache.h"
+#include "../string_func.h"
+
+/** Font cache for mocking basic use of fonts. */
+class MockFontCache : public FontCache {
+public:
+	MockFontCache(FontSize fs) : FontCache(fs)
+	{
+		this->height = FontCache::GetDefaultFontHeight(this->fs);
+	}
+
+	void SetUnicodeGlyph(char32_t, SpriteID) override {}
+	void InitializeUnicodeGlyphMap() override {}
+	void ClearFontCache() override {}
+	const Sprite *GetGlyph(GlyphID) override { return nullptr; }
+	uint GetGlyphWidth(GlyphID) override { return this->height / 2; }
+	bool GetDrawGlyphShadow() override { return false; }
+	GlyphID MapCharToGlyph(char32_t key) override { return key; }
+	const void *GetFontTable(uint32_t, size_t &length) override { length = 0; return nullptr; }
+	std::string GetFontName() override { return "mock"; }
+	bool IsBuiltInFont() override { return true; }
+
+	static void InitializeFontCaches()
+	{
+		for (FontSize fs = FS_BEGIN; fs != FS_END; fs++) {
+			if (FontCache::caches[fs] == nullptr) new MockFontCache(fs); /* FontCache inserts itself into to the cache. */
+		}
+	}
+};
+
+#endif /* MOCK_FONTCACHE_H */