Add support for asserting on multiple snapshotting strategy (#150)

Author: mackoj

Sources/SnapshotTesting/AssertSnapshot.swift

@@ -45,6 +45,73 @@ public func assertSnapshot<Value, Format>(
   XCTFail(message, file: file, line: line)
 }
 
+/// Asserts that a given value matches a reference on disk.
+///
+/// - Parameters:
+///   - value: A value to compare against a reference.
+///   - snapshotting: An dictionnay of names and strategies for serializing, deserializing, and comparing values.
+///   - recording: Whether or not to record a new reference.
+///   - timeout: The amount of time a snapshot must be generated in.
+///   - file: The file in which failure occurred. Defaults to the file name of the test case in which this function was called.
+///   - testName: The name of the test in which failure occurred. Defaults to the function name of the test case in which this function was called.
+///   - line: The line number on which failure occurred. Defaults to the line number on which this function was called.
+public func assertSnapshots<Value, Format>(
+  matching value: @autoclosure () throws -> Value,
+  as strategies: [String: Snapshotting<Value, Format>],
+  record recording: Bool = false,
+  timeout: TimeInterval = 5,
+  file: StaticString = #file,
+  testName: String = #function,
+  line: UInt = #line
+  ) {
+
+  strategies.forEach { name, strategy in
+    assertSnapshot(
+      matching: value,
+      as: strategy,
+      named: name,
+      record: recording,
+      timeout: timeout,
+      file: file,
+      testName: testName,
+      line: line
+    )
+  }
+}
+
+/// Asserts that a given value matches a reference on disk.
+///
+/// - Parameters:
+///   - value: A value to compare against a reference.
+///   - snapshotting: An array of strategies for serializing, deserializing, and comparing values.
+///   - recording: Whether or not to record a new reference.
+///   - timeout: The amount of time a snapshot must be generated in.
+///   - file: The file in which failure occurred. Defaults to the file name of the test case in which this function was called.
+///   - testName: The name of the test in which failure occurred. Defaults to the function name of the test case in which this function was called.
+///   - line: The line number on which failure occurred. Defaults to the line number on which this function was called.
+public func assertSnapshots<Value, Format>(
+  matching value: @autoclosure () throws -> Value,
+  as strategies: [Snapshotting<Value, Format>],
+  record recording: Bool = false,
+  timeout: TimeInterval = 5,
+  file: StaticString = #file,
+  testName: String = #function,
+  line: UInt = #line
+  ) {
+
+  strategies.forEach { strategy in
+    assertSnapshot(
+      matching: value,
+      as: strategy,
+      record: recording,
+      timeout: timeout,
+      file: file,
+      testName: testName,
+      line: line
+    )
+  }
+}
+
 /// Verifies that a given value matches a reference on disk.
 ///
 /// - Parameters:

Tests/SnapshotTestingTests/SnapshotTestingTests.swift

@@ -250,6 +250,28 @@ class SnapshotTestingTests: TestCase {
     #endif
   }
 
+  func testAssertMultipleSnapshot() {
+    #if os(iOS)
+    class TableViewController: UITableViewController {
+      override func viewDidLoad() {
+        super.viewDidLoad()
+        self.tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
+      }
+      override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
+        return 10
+      }
+      override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
+        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
+        cell.textLabel?.text = "\(indexPath.row)"
+        return cell
+      }
+    }
+    let tableViewController = TableViewController()
+    assertSnapshots(matching: tableViewController, as: ["iPhoneSE-image" : .image(on: .iPhoneSe), "iPad-image" : .image(on: .iPadMini)])
+    assertSnapshots(matching: tableViewController, as: [.image(on: .iPhoneX), .image(on: .iPhoneXsMax)])
+    #endif
+  }
+
   func testTraits() {
     #if os(iOS) || os(tvOS)
     if #available(iOS 11.0, tvOS 11.0, *) {