New avatar colors + tests

.github/workflows/tests.yml

@@ -0,0 +1,19 @@
+# This workflow will build a Swift project
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-swift
+
+name: Tests
+
+on:
+  pull_request:
+    branches: [ "main" ]
+
+jobs:
+  tests:
+
+    runs-on: macos-13
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Run tests
+      run: xcodebuild test -scheme 'Compound' -sdk iphonesimulator -destination 'platform=iOS Simulator,name=iPhone 14'
+

Sources/Compound/Colors/CompoundColors.swift

@@ -92,6 +92,26 @@ public struct CompoundColors {
     public let bgSubtleSecondaryLevel0 = Color(UIColor { $0.isLight ? UIColor(compound.colorGray300) : UIColor(compound.colorThemeBg) })
     public let bgCanvasDefaultLevel1 = Color(UIColor { $0.isLight ? UIColor(compound.colorThemeBg) : UIColor(compound.colorGray300) })
 
+    // MARK: - Avatar Colors
+    // Used to determine the background color and the foreground color of an avatar.
+
+    // Order matches the one from web
+    // https://github.com/vector-im/compound-web/blob/5dda11aa9733462fb8422968181275bc3e9b35e3/src/components/Avatar/Avatar.module.css#L64
+    internal let avatarColors: [AvatarColor] = [
+        .init(background: compound.colorBlue300, foreground: compound.colorBlue1200),
+        .init(background: compound.colorFuchsia300, foreground: compound.colorFuchsia1200),
+        .init(background: compound.colorGreen300, foreground: compound.colorGreen1200),
+        .init(background: compound.colorPink300, foreground: compound.colorPink1200),
+        .init(background: compound.colorOrange300, foreground: compound.colorOrange1200),
+        .init(background: compound.colorCyan300, foreground: compound.colorCyan1200),
+        .init(background: compound.colorPurple300, foreground: compound.colorPurple1200),
+        .init(background: compound.colorLime300, foreground: compound.colorLime1200)
+    ]
+
+    public func avatarColor(for contentID: String) -> AvatarColor {
+        avatarColors[contentID.hashCode]
+    }
+
     // MARK: - Awaiting Semantic Tokens
 
     /// This token is a placeholder and hasn't been finalised.
@@ -125,3 +145,19 @@ private extension UITraitCollection {
     /// Whether or not the trait collection contains a `userInterfaceStyle` of `.light`.
     var isLight: Bool { userInterfaceStyle == .light }
 }
+
+public struct AvatarColor: Equatable {
+    let background: Color
+    let foreground: Color
+}
+
+private extension String {
+    /// Calculates a numeric hash same as Element Web
+    /// See original function here https://github.com/matrix-org/matrix-react-sdk/blob/321dd49db4fbe360fc2ff109ac117305c955b061/src/utils/FormattingUtils.js#L47
+    var hashCode: Int {
+        let characterCodeSum = self.reduce(0) { sum, character in
+            sum + Int(character.unicodeScalars.first?.value ?? 0)
+        }
+        return (characterCodeSum % Color.compound.avatarColors.count)
+    }
+}

Tests/CompoundTests/AvatarColorsTests.swift

@@ -0,0 +1,46 @@
+//
+//  File.swift
+//  
+//
+//  Created by Mauro Romito on 31/08/23.
+//
+
+import Foundation
+
+@testable import Compound
+import SwiftUI
+import XCTest
+
+final class AvatarColorsTests: XCTestCase {
+    struct TestCase {
+        let input: String
+        private let webOutput: Int
+
+        // remember that web starts the index from 1 while we start from 0
+        var output: Int {
+            webOutput - 1
+        }
+
+        init(input: String, webOutput: Int) {
+            self.input = input
+            self.webOutput = webOutput
+        }
+    }
+
+    func testAvatarColorHash() {
+        // Match the tests with the web ones for consistency between the two platforms
+        // https://github.com/vector-im/compound-web/blob/5dda11aa9733462fb8422968181275bc3e9b35e3/src/components/Avatar/Avatar.test.tsx#L62
+        let testCases: [TestCase] = [
+            .init(input: "@bob:example.org", webOutput: 8),
+            .init(input: "@alice:example.org", webOutput: 3),
+            .init(input: "@charlie:example.org", webOutput: 5),
+            .init(input: "@dan:example.org", webOutput: 8),
+            .init(input: "@elena:example.org", webOutput: 2),
+            .init(input: "@fanny:example.org", webOutput: 1)
+        ]
+
+        for testCase in testCases {
+            XCTAssertEqual(Color.compound.avatarColor(for: testCase.input), Color.compound.avatarColors[testCase.output])
+        }
+    }
+}