Write unit tests for Color+Extension.swift (#101)

- Wrote tests
- Possible minor bug where there's an alpha missing on 32-bit colors?

Sources/SwiftUICharts/Base/Extensions/Color+Extension.swift

@@ -12,6 +12,8 @@ extension Color {
         case 6: // RGB (24-bit)
             (red, green, blue) = (int >> 16, int >> 8 & 0xFF, int & 0xFF)
         case 8: // ARGB (32-bit)
+            // FIXME: I think we need an an alpha value on this one. See link below.
+            // https://stackoverflow.com/a/56874327/4475605
             (red, green, blue) = (int >> 16 & 0xFF, int >> 8 & 0xFF, int & 0xFF)
         default:
             (red, green, blue) = (0, 0, 0)

Tests/SwiftUIChartsTests/ColorExtensionTests.swift

@@ -0,0 +1,56 @@
+//
+//  ColorExtensionTests.swift
+//  SwiftUIChartsTests
+//
+//  Created by Adrian Bolinger on 5/24/20.
+//
+
+@testable import SwiftUICharts
+import SwiftUI
+import XCTest
+
+class ColorExtensionTests: XCTestCase {
+    func testTwentyFourBitRGBColors() {
+        let actualWhite = Color(hexString: "FFFFFF")
+        let expectedWhite = Color(red: 1, green: 1, blue: 1)
+        XCTAssertEqual(actualWhite, expectedWhite)
+        
+        let actualBlack = Color(hexString: "000000")
+        let expectedBlack = Color(red: 0, green: 0, blue: 0)
+        XCTAssertEqual(actualBlack, expectedBlack)
+        
+        let actualRed = Color(hexString: "FF0000")
+        let expectedRed = Color(red: 255/255, green: 0, blue: 0)
+        XCTAssertEqual(actualRed, expectedRed)
+        
+        let actualGreen = Color(hexString: "00FF00")
+        let expectedGreen = Color(red: 0, green: 1, blue: 0)
+        XCTAssertEqual(actualGreen, expectedGreen)
+        
+        let actualBlue = Color(hexString: "0000FF")
+        let expectedBlue = Color(red: 0, green: 0, blue: 1)
+        XCTAssertEqual(actualBlue, expectedBlue)
+    }
+    
+    func testTwelveBitRGBColors() {
+        let actualWhite = Color(hexString: "FFF")
+        let expectedWhite = Color(red: 1, green: 1, blue: 1)
+        XCTAssertEqual(actualWhite, expectedWhite)
+        
+        let actualBlack = Color(hexString: "000")
+        let expectedBlack = Color(red: 0, green: 0, blue: 0)
+        XCTAssertEqual(actualBlack, expectedBlack)
+        
+        let actualRed = Color(hexString: "F00")
+        let expectedRed = Color(red: 255/255, green: 0, blue: 0)
+        XCTAssertEqual(actualRed, expectedRed)
+        
+        let actualGreen = Color(hexString: "0F0")
+        let expectedGreen = Color(red: 0, green: 1, blue: 0)
+        XCTAssertEqual(actualGreen, expectedGreen)
+        
+        let actualBlue = Color(hexString: "00F")
+        let expectedBlue = Color(red: 0, green: 0, blue: 1)
+        XCTAssertEqual(actualBlue, expectedBlue)
+    }
+}