Add fallback font unittests for different base fonts

This CL is adding unittests for GetFallbackFont(...) API.
The goal is to increase coverage of the fallback font code
for cases where the base font is not the default system
font.

Some chrome users are changing their default system font
which may create bad cases for fallback fonts API.

There are two unittests that required change:
  1) Lao (u+0ED0)
  2) Nko (u+07C1)
In these two cases, the codepoint is present in "Segeo UI"
but is not present in "Segeo UI Italic".

Change-Id: Id9c50be56e025ae0c4a4651b1e2c47812430015d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1948091
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Reviewed-by: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721500}

ui/gfx/font_fallback_unittest.cc

@@ -8,6 +8,7 @@
 
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
 #include "base/test/task_environment.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -37,8 +38,20 @@ const FallbackFontTestOption default_fallback_option = {false, false, false};
 // Options for tests that does not validate the GetFallbackFont(...) parameters.
 const FallbackFontTestOption untested_fallback_option = {true, true, true};
 
-using FallbackFontTestParamInfo =
-    std::tuple<FallbackFontTestCase, FallbackFontTestOption>;
+struct BaseFontTestOption {
+  const char* family_name = nullptr;
+  int delta = 0;
+  int style = 0;
+  Font::Weight weight = Font::Weight::NORMAL;
+};
+
+constexpr BaseFontTestOption default_base_font;
+constexpr BaseFontTestOption styled_font = {nullptr, 1, Font::FontStyle::ITALIC,
+                                            Font::Weight::BOLD};
+constexpr BaseFontTestOption sans_font = {"sans", 2};
+
+using FallbackFontTestParamInfo = std::
+    tuple<FallbackFontTestCase, FallbackFontTestOption, BaseFontTestOption>;
 
 class GetFallbackFontTest
     : public ::testing::TestWithParam<FallbackFontTestParamInfo> {
@@ -48,14 +61,27 @@ class GetFallbackFontTest
   static std::string ParamInfoToString(
       ::testing::TestParamInfo<FallbackFontTestParamInfo> param_info) {
     const FallbackFontTestCase& test_case = std::get<0>(param_info.param);
+    const BaseFontTestOption& base_font_option = std::get<2>(param_info.param);
+
+    std::string font_option;
+    if (base_font_option.family_name)
+      font_option += std::string("F") + base_font_option.family_name;
+    if (base_font_option.delta || base_font_option.style ||
+        base_font_option.style) {
+      font_option +=
+          base::StringPrintf("_d%ds%dw%d", base_font_option.delta,
+                             base_font_option.style, base_font_option.weight);
+    }
 
     std::string language_tag = test_case.language_tag;
     base::RemoveChars(language_tag, "-", &language_tag);
     return std::string("S") + uscript_getName(test_case.script) + "L" +
-           language_tag;
+           language_tag + font_option;
   }
 
-  void SetUp() override { std::tie(test_case_, test_option_) = GetParam(); }
+  void SetUp() override {
+    std::tie(test_case_, test_option_, base_font_option_) = GetParam();
+  }
 
  protected:
   bool GetFallbackFont(const Font& font,
@@ -115,6 +141,7 @@ class GetFallbackFontTest
 
   FallbackFontTestCase test_case_;
   FallbackFontTestOption test_option_;
+  BaseFontTestOption base_font_option_;
   std::string script_name_;
 
  private:
@@ -143,7 +170,16 @@ class GetFallbackFontTest
 #endif
 TEST_P(GetFallbackFontTest, MAYBE_GetFallbackFont) {
   // Default system font.
-  const Font base_font;
+  Font base_font;
+  // Apply font options to the base font.
+  if (base_font_option_.family_name)
+    base_font = Font(base_font_option_.family_name, base_font.GetFontSize());
+  if (base_font_option_.delta != 0 || base_font_option_.style != 0 ||
+      base_font_option_.weight != gfx::Font::Weight::NORMAL) {
+    base_font =
+        base_font.Derive(base_font_option_.delta, base_font_option_.style,
+                         base_font_option_.weight);
+  }
 
 #if defined(OS_WIN)
   // Skip testing this call to GetFallbackFont on older windows versions. Some
@@ -229,8 +265,10 @@ std::vector<FallbackFontTestCase> GetSampleFontTestCases() {
 INSTANTIATE_TEST_SUITE_P(
     KnownExpectedFonts,
     GetFallbackFontTest,
-    testing::Combine(testing::ValuesIn(kGetFontFallbackTests),
-                     testing::Values(default_fallback_option)),
+    testing::Combine(
+        testing::ValuesIn(kGetFontFallbackTests),
+        testing::Values(default_fallback_option),
+        testing::Values(default_base_font, styled_font, sans_font)),
     GetFallbackFontTest::ParamInfoToString);
 
 // Ensures that font fallback functions are working properly for any string
@@ -242,7 +280,8 @@ INSTANTIATE_TEST_SUITE_P(
     Glyphs,
     GetFallbackFontTest,
     testing::Combine(testing::ValuesIn(GetSampleFontTestCases()),
-                     testing::Values(untested_fallback_option)),
+                     testing::Values(untested_fallback_option),
+                     testing::Values(default_base_font)),
     GetFallbackFontTest::ParamInfoToString);
 
 }  // namespace gfx

ui/gfx/test/font_fallback_test_data.cc

@@ -158,7 +158,10 @@ std::vector<FallbackFontTestCase> kGetFontFallbackTests = {
      {"Segoe UI Historic"},
      kWin10Only},
 
-    {USCRIPT_LAO, "lo", L"\u0ED0\u0ED1", {"Lao UI", "Leelawadee UI"}},
+    {USCRIPT_LAO,
+     "lo",
+     L"\u0ED0\u0ED1",
+     {"Lao UI", "Leelawadee UI", "Segoe UI"}},
     {USCRIPT_LISU, "lis", L"\uA4D0\uA4D1", {"Segoe UI"}, kWin10Only},
 
     {USCRIPT_LYCIAN,
@@ -183,7 +186,7 @@ std::vector<FallbackFontTestCase> kGetFontFallbackTests = {
 
     {USCRIPT_MYANMAR, "my", L"\u1000\u1001", {"Myanmar Text"}, kWin10Only},
     {USCRIPT_NEW_TAI_LUE, "", L"\u1981\u1982", {"Microsoft New Tai Lue"}},
-    {USCRIPT_NKO, "nko", L"\u07C1\u07C2", {"Ebrima"}},
+    {USCRIPT_NKO, "nko", L"\u07C1\u07C2", {"Ebrima", "Segoe UI"}},
 
     {USCRIPT_OGHAM,
      "",