Implement progress element for Slipstream

Sources/Slipstream/W3C/Elements/Forms/ProgressView.swift

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+import SwiftSoup
+
+/// A view that displays an indicator showing the completion progress of a task.
+///
+/// The `ProgressView` represents an HTML `<progress>` element, which displays
+/// progress towards completion of a task. It can be used to show determinate
+/// progress (with a specific value) or indeterminate progress (when the value
+/// is unknown).
+///
+/// ```swift
+/// // Indeterminate progress (no value specified)
+/// ProgressView()
+///
+/// // Determinate progress with default max (1.0)
+/// ProgressView(value: 0.7)
+///
+/// // Custom value and max
+/// ProgressView(value: 70, max: 100)
+/// ```
+///
+/// - SeeAlso: W3C [progress](https://html.spec.whatwg.org/multipage/form-elements.html#the-progress-element) specification.
+@available(iOS 17.0, macOS 14.0, *)
+public struct ProgressView: View {
+  /// Creates a progress indicator.
+  ///
+  /// - Parameters:
+  ///   - value: The current progress value. When `nil`, the progress indicator
+  ///     is indeterminate, indicating that an activity is ongoing with no
+  ///     indication of how long it is expected to take. When specified, the value
+  ///     must be between 0 and `max`.
+  ///   - max: The maximum value, representing task completion. When `nil`, the
+  ///     W3C default of 1.0 is used, allowing you to specify values as percentages
+  ///     (e.g., 0.7 for 70%). When specified, must be greater than 0.
+  public init(value: Double? = nil, max: Double? = nil) {
+    self.value = value
+    self.max = max
+  }
+
+  @_documentation(visibility: private)
+  public func render(_ container: Element, environment: EnvironmentValues) throws {
+    let element = try container.appendElement("progress")
+
+    if let value {
+      try element.attr("value", String(value))
+    }
+    if let max {
+      try element.attr("max", String(max))
+    }
+  }
+
+  private let value: Double?
+  private let max: Double?
+}

Tests/SlipstreamTests/W3C/Forms/ProgressViewTests.swift

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+import Testing
+
+import Slipstream
+
+struct ProgressViewTests {
+  @Test func indeterminate() throws {
+    try #expect(renderHTML(ProgressView()) == #"<progress></progress>"#)
+  }
+
+  @Test func withValue() throws {
+    try #expect(renderHTML(ProgressView(value: 0.7)) == #"<progress value="0.7"></progress>"#)
+  }
+
+  @Test func withCustomMax() throws {
+    try #expect(renderHTML(ProgressView(max: 100)) == #"<progress max="100.0"></progress>"#)
+  }
+
+  @Test func withValueAndMax() throws {
+    try #expect(renderHTML(ProgressView(value: 70, max: 100)) == #"<progress value="70.0" max="100.0"></progress>"#)
+  }
+
+  @Test func zeroValue() throws {
+    try #expect(renderHTML(ProgressView(value: 0, max: 100)) == #"<progress value="0.0" max="100.0"></progress>"#)
+  }
+
+  @Test func fullValue() throws {
+    try #expect(renderHTML(ProgressView(value: 100, max: 100)) == #"<progress value="100.0" max="100.0"></progress>"#)
+  }
+
+  @Test func percentageUseCase() throws {
+    // Using default max of 1.0 for percentage-style progress
+    try #expect(renderHTML(ProgressView(value: 0.0)) == #"<progress value="0.0"></progress>"#)
+    try #expect(renderHTML(ProgressView(value: 0.5)) == #"<progress value="0.5"></progress>"#)
+    try #expect(renderHTML(ProgressView(value: 1.0)) == #"<progress value="1.0"></progress>"#)
+  }
+
+  @Test func numericUseCase() throws {
+    // Using custom max for numeric progress tracking
+    try #expect(renderHTML(ProgressView(value: 25, max: 100)) == #"<progress value="25.0" max="100.0"></progress>"#)
+    try #expect(renderHTML(ProgressView(value: 50, max: 100)) == #"<progress value="50.0" max="100.0"></progress>"#)
+    try #expect(renderHTML(ProgressView(value: 75, max: 100)) == #"<progress value="75.0" max="100.0"></progress>"#)
+  }
+}