Resolve #275 - Color class with tests and formatting

Author: craigfowler

CSF.Screenplay.Selenium/Color.cs

@@ -125,6 +125,72 @@ public override bool Equals(object obj)
         }
 #endif
 
+        /// <summary>
+        /// Gets a representation of the current instance in the format <c>rgb(RRR, GGG, BBB)</c>.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// The characters <c>RRR</c>, <c>GGG</c> and <c>BBB</c> in the format example correpsond to three decimal
+        /// unsigned byte values (0 to 255) which indicate the red, green and blue components of the color respectively.
+        /// </para>
+        /// <para>
+        /// Note that this format omits the alpha (transparency) component of the color.  Thus, the resulting string
+        /// will not be equal to the <see cref="Color"/> value which created it if the alpha component is not equal to 1.
+        /// The only string-formatting methods which preserve all of the information in the color instance are
+        /// <see cref="ToRgbaString"/> and the default <see cref="ToString"/> method, which both return equivalent results.
+        /// </para>
+        /// </remarks>
+        /// <returns>An RGB-format string.</returns>
+        public string ToRgbString() => $"rgb({Red}, {Green}, {Blue})";
+
+        /// <summary>
+        /// Gets a representation of the current instance in the format <c>rgba(RRR, GGG, BBB, A)</c>.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// The characters <c>RRR</c>, <c>GGG</c> and <c>BBB</c> in the format example correpsond to three decimal
+        /// unsigned byte values (0 to 255) which indicate the red, green and blue components of the color respectively.
+        /// The character <c>A</c> corresponds to the alpha (transparency) component of the color.  It will be either
+        /// the numbers 1 or 0, or it will be a decimal number between one and zero.
+        /// </para>
+        /// <para>
+        /// Out of the string-formatting methods available on the <see cref="Color"/> type, only this one and the default
+        /// <see cref="ToString"/> method preserve all information in the color instance.  Thus this method may be used
+        /// alongside <see cref="Parse"/> or <see cref="TryParse(string, out Color)"/> to reliably round-trip an RGBA
+        /// string color representation.
+        /// </para>
+        /// </remarks>
+        /// <returns>An RGBA-format string.</returns>
+        public string ToRgbaString() => $"rgba({Red}, {Green}, {Blue}, {Alpha})";
+
+        /// <summary>
+        /// Gets a representation of the current instance in the format <c>#RRGGBB</c>.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// The characters <c>RR</c>, <c>GG</c> and <c>BB</c> in the format example correpsond to three hexadecimal
+        /// unsigned byte values (00 to FF, corresponding to decimal 0 to 255).  These indicate the red, green and
+        /// blue components of the color respectively.
+        /// </para>
+        /// <para>
+        /// Note that this format omits the alpha (transparency) component of the color.  Thus, the resulting string
+        /// will not be equal to the <see cref="Color"/> value which created it if the alpha component is not equal to 1.
+        /// The only string-formatting methods which preserve all of the information in the color instance are
+        /// <see cref="ToRgbaString"/> and the default <see cref="ToString"/> method, which both return equivalent results.
+        /// </para>
+        /// </remarks>
+        /// <returns>An RGB-format string.</returns>
+        public string ToHexString() => $"#{Red:X}{Green:X}{Blue:X}";
+
+        /// <summary>
+        /// Returns a string in the same format as <see cref="ToRgbaString"/>.
+        /// </summary>
+        /// <remarks>
+        /// <para>This method and <see cref="ToRgbaString"/> are equivalent.</para>
+        /// </remarks>
+        /// <returns>An RGBA-format string.</returns>
+        public override string ToString() => ToRgbaString();
+
         /// <inheritdoc/>
         public override int GetHashCode() => HashCode.Combine(Red, Green, Blue, Alpha);
 

Tests/CSF.Screenplay.Selenium.Tests/ColorTests.cs

@@ -1,5 +1,4 @@
 using System;
-using Microsoft.AspNetCore.Mvc;
 
 namespace CSF.Screenplay.Selenium;
 
@@ -185,4 +184,31 @@ public void OpInequalityShouldReturnTrueForAColorAndASysColorIfTheyAreNotRgbaEqu
     {
         Assert.That(() => Color.Parse(first) != System.Drawing.Color.FromArgb(r, g, b), Is.True);
     }
+
+    [TestCase("rgb(30, 128, 55)")]
+    public void ParseFollowedByToRgbStringShouldRoundtripTheColor(string colorString)
+    {
+        Assert.That(() => Color.Parse(colorString).ToRgbString(), Is.EqualTo(colorString));
+    }
+
+    [TestCase("rgba(30, 128, 55, 0.5)")]
+    [TestCase("rgba(30, 128, 55, 1)")]
+    [TestCase("rgba(0, 0, 0, 0)")]
+    public void ParseFollowedByToRgbaStringShouldRoundtripTheColor(string colorString)
+    {
+        Assert.That(() => Color.Parse(colorString).ToRgbaString(), Is.EqualTo(colorString));
+    }
+
+    [TestCase("rgba(30, 128, 55, 0.5)")]
+    [TestCase("rgba(30, 128, 55, 1)")]
+    [TestCase("rgba(0, 0, 0, 0)")]
+    public void ParseFollowedByToStringShouldRoundtripTheColor(string colorString)
+    {
+        Assert.That(() => Color.Parse(colorString).ToString(), Is.EqualTo(colorString));
+    }
+    [TestCase("#E055D8")]
+    public void ParseFollowedByToHexStringShouldRoundtripTheColor(string colorString)
+    {
+        Assert.That(() => Color.Parse(colorString).ToHexString(), Is.EqualTo(colorString));
+    }
 }

Tests/CSF.Screenplay.Selenium.Tests/ColorsTests.cs

@@ -0,0 +1,25 @@
+namespace CSF.Screenplay.Selenium;
+
+[TestFixture, Parallelizable]
+public class ColorsTests
+{
+    [TestCase("GREEN", 0, 128, 0)]
+    [TestCase("green", 0, 128, 0)]
+    [TestCase("gReEn", 0, 128, 0)]
+    public void GetNamedColorShouldReturnAColorIfTheNameIsValid(string colorName, byte r, byte g, byte b)
+    {
+        Assert.That(() => Colors.GetNamedColor(colorName), Is.EqualTo(new Color(r, g, b)));
+    }
+
+    [Test]
+    public void GetNamedColorShouldThrowAneIfTheNameIsNull()
+    {
+        Assert.That(() => Colors.GetNamedColor(null), Throws.ArgumentNullException);
+    }
+
+    [Test]
+    public void GetNamedColorShouldThrowArgExIfTheNameIsInvalid()
+    {
+        Assert.That(() => Colors.GetNamedColor("ElephantsAreNotAColor"), Throws.ArgumentException);
+    }
+}