[#66557] Make #rgb_colors handle invalid hexcodes

Ensures dependent methods such as `#darken` do not blow up if a hexcode
value is invalid (which can occur if the record is unpersisted or fails
validation). Missing/invalid R, G, B component values will now be
handled as zero.

app/models/colors/hex_color.rb

@@ -76,11 +76,13 @@ module Colors
     end
 
     ##
-    # Splits the hexcode into rbg color array
+    # Splits the hexcode into rgb color array
     def rgb_colors
       hexcode
-        .delete("#") # Remove trailing #
+        .delete_prefix("#") # Remove leading #
+        .ljust(6, "0") # Pad to at least 6 chars
         .scan(/../) # Pair hex chars
+        .first(3)
         .map(&:hex) # to int
     end
 

spec/models/colors/hex_color_spec.rb

@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program 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; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program 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 this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require "spec_helper"
+
+RSpec.describe Colors::HexColor do
+  let(:color_class) { Data.define(:hexcode).include(described_class) }
+
+  describe "#rgb_colors" do
+    context "when hexcode is valid" do
+      it "returns an RGB array" do
+        expect(color_class.new(hexcode: "#FF69B4").rgb_colors).to eq [255, 105, 180]
+      end
+    end
+
+    context "when hexcode is too short" do
+      it "returns an RGB array, zeroing missing component values" do
+        expect(color_class.new(hexcode: "#ff").rgb_colors).to eq [255, 0, 0]
+      end
+    end
+
+    context "when hexcode is too long" do
+      it "returns an RGB array, dropping extra values" do
+        expect(color_class.new(hexcode: "#ff3366AA").rgb_colors).to eq [255, 51, 102]
+      end
+    end
+
+    context "when hexcode is invalid" do
+      it "returns an RGB array, zeroing invalid component values" do
+        expect(color_class.new(hexcode: "#eeXXcd").rgb_colors).to eq [238, 0, 205]
+      end
+    end
+  end
+
+  describe "#darken" do
+    context "when hexcode is valid" do
+      it "returns the darkened color's hexcode" do
+        expect(color_class.new(hexcode: "#663399").darken(0.5)).to eq "#331a4d"
+      end
+    end
+
+    context "when hexcode is invalid" do
+      it "zeroes missing component values and returns the darkened color's hexcode" do
+        expect(color_class.new(hexcode: "#eeXXcd").darken(0.5)).to eq "#770067"
+      end
+    end
+  end
+
+  describe "#lighten" do
+    context "when hexcode is valid" do
+      it "returns the lightened color's hexcode" do
+        expect(color_class.new(hexcode: "#663399").lighten(0.5)).to eq "#b399cc"
+      end
+    end
+
+    context "when hexcode is invalid" do
+      it "zeroes missing component values and returns the darkened color's hexcode" do
+        expect(color_class.new(hexcode: "#eeXXcd").lighten(0.5)).to eq "#f780e6"
+      end
+    end
+  end
+end