Validate Modifier for Predicates (#42)

# Validate Modifier for Predicates

## ♻️ Current situation & Problem
SpeziValidation currently provides the `validate(input:rules:)` modifier
to validate `String`-based inputs using SpeziValidation. This PR extends
this functionality to `Bool` expressions. The new `validate(_:message:)`
modifier can be used to validate all sorts of boolean conditions and
supply a validation failure reason with it.

## ⚙️ Release Notes 
* New `validate(_:message:)` modifier to validate bool expressions.


## 📚 Documentation
Documentation was updated to highlight the new modifier.


## ✅ Testing
_TBA_


## 📝 Code of Conduct & Contributing Guidelines 

By submitting creating this pull request, you agree to follow our [Code
of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md):
- [x] I agree to follow the [Code of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md).

Package.swift

@@ -98,7 +98,7 @@ func swiftLintPlugin() -> [Target.PluginUsage] {
 
 func swiftLintPackage() -> [PackageDescription.Package.Dependency] {
     if ProcessInfo.processInfo.environment["SPEZI_DEVELOPMENT_SWIFTLINT"] != nil {
-        [.package(url: "https://github.com/realm/SwiftLint.git", .upToNextMinor(from: "0.55.1"))]
+        [.package(url: "https://github.com/realm/SwiftLint.git", from: "0.55.1")]
     } else {
         []
     }

Sources/SpeziValidation/SpeziValidation.docc/SpeziValidation.md

@@ -81,6 +81,7 @@ var body: some View {
 - ``ValidationRule``
 - ``SwiftUI/View/validate(input:rules:)-5dac4``
 - ``SwiftUI/View/validate(input:rules:)-9vks0``
+- ``SwiftUI/View/validate(_:message:)``
 
 ### Managing Validation
 

Sources/SpeziValidation/ValidationModifier.swift

@@ -109,4 +109,59 @@ extension View {
     public func validate(input value: String, rules: ValidationRule...) -> some View {
         validate(input: value, rules: rules)
     }
+
+
+    /// Validate a `Bool` expression.
+    ///
+    /// This modifier can be used to validate a `Bool` predicate. If the expression doesn't evaluate to `true`, the `message`
+    /// is shown as a validation error.
+    ///
+    /// Validation is managed through a ``ValidationEngine`` instance that is injected as an `Observable` into the
+    /// environment.
+    ///
+    /// Below is an example that uses the `validate(_:message:)` modifier to validate the selection of a `Picker`.
+    /// - Note: The example uses the ``receiveValidation(in:)`` modifier to retrieve the validation results of the subview.
+    ///     The ``ValidationResultsView`` is used to render the failure reason in red text below the picker.
+    ///
+    /// ```swift
+    /// struct MyView: View {
+    ///     enum Selection: String, CaseIterable, Hashable {
+    ///         case none = "Nothing selected"
+    ///         case accept = "Accept"
+    ///         case deny = "Deny"
+    ///     }
+    ///
+    ///     @State private var selection: Selection = .none
+    ///     @ValidationState private var validationState
+    ///
+    ///     var body: some View {
+    ///         VStack(alignment: .leading) {
+    ///             Picker(selection: $selection) {
+    ///                 ForEach(Selection.allCases, id: \.rawValue) { selection in
+    ///                     Text(selection.rawValue)
+    ///                         .tag(selection)
+    ///                 }
+    ///             } label: {
+    ///                 Text("Cookies")
+    ///             }
+    ///             ValidationResultsView(results: validationState.allDisplayedValidationResults)
+    ///         }
+    ///             .validate(selection != .none, message: "This field must be selected")
+    ///             .receiveValidation(in: $validationState)
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// - Important: You shouldn't place multiple validate modifiers into the same view hierarchy branch. This creates
+    ///     visibility problems in both direction. Both displaying validation results in the child view and receiving
+    ///     validation state from the parent view.
+    ///
+    /// - Parameters:
+    ///   - predicate: The predicate to validate.
+    ///   - message: The validation message that is used as an failure reason, if the predicate evaluates to `false`.
+    /// - Returns: The modified view.
+    public func validate(_ predicate: Bool, message: LocalizedStringResource) -> some View {
+        let rule = ValidationRule(rule: { $0.isEmpty }, message: message)
+        return validate(input: predicate ? "" : "FALSE", rules: [rule])
+    }
 }

Tests/UITests/TestApp/Localizable.xcstrings

@@ -31,6 +31,9 @@
     },
     "Condition present" : {
 
+    },
+    "Cookies" : {
+
     },
     "Credentials" : {
 
@@ -153,6 +156,9 @@
     },
     "Targets" : {
 
+    },
+    "This field must be selected." : {
+
     },
     "This is a default error description!" : {
 

Tests/UITests/TestApp/ValidationTests/SpeziValidationTests.swift

@@ -6,21 +6,23 @@
 // SPDX-License-Identifier: MIT
 //
 
-import SpeziPersonalInfo
 import SwiftUI
 import XCTestApp
 
 
 enum SpeziValidationTests: String, TestAppTests {
     case validation = "Validation"
     case validationRules = "ValidationRules"
+    case validationPredicate = "Validation Picker"
 
     func view(withNavigationPath path: Binding<NavigationPath>) -> some View {
         switch self {
         case .validation:
             FocusedValidationTests()
         case .validationRules:
             DefaultValidationRules()
+        case .validationPredicate:
+            ValidationPredicateTests()
         }
     }
 }

Tests/UITests/TestApp/ValidationTests/ValidationPredicateTests.swift

@@ -0,0 +1,40 @@
+//
+// This source file is part of the Stanford Spezi open-source project
+//
+// SPDX-FileCopyrightText: 2024 Stanford University and the project authors (see CONTRIBUTORS.md)
+//
+// SPDX-License-Identifier: MIT
+//
+
+import SpeziValidation
+import SwiftUI
+
+
+struct ValidationPredicateTests: View {
+    enum Selection: String, CaseIterable, Hashable {
+        case none = "Nothing selected"
+        case accept = "Accept"
+        case deny = "Deny"
+    }
+
+    @State private var selection: Selection = .none
+    @ValidationState private var validationState
+
+    var body: some View {
+        List {
+            VStack(alignment: .leading) {
+                Picker(selection: $selection) {
+                    ForEach(Selection.allCases, id: \.rawValue) { selection in
+                        Text(selection.rawValue)
+                            .tag(selection)
+                    }
+                } label: {
+                    Text("Cookies")
+                }
+                ValidationResultsView(results: validationState.allDisplayedValidationResults)
+            }
+                .validate(selection != .none, message: "This field must be selected.")
+                .receiveValidation(in: $validationState)
+        }
+    }
+}

Tests/UITests/TestApp/ViewsTests/MarkdownViewTestView.swift

@@ -16,8 +16,8 @@ struct MarkdownViewTestView: View {
     var body: some View {
         MarkdownView(
             asyncMarkdown: {
-                try? await Task.sleep(for: .seconds(5))
-                return Data("This is a *markdown* **example** taking 5 seconds to load.".utf8)
+                try? await Task.sleep(for: .seconds(2))
+                return Data("This is a *markdown* **example** taking 2 seconds to load.".utf8)
             }
         )
         MarkdownView(

Tests/UITests/TestAppUITests/SpeziPersonalInfo/PersonalInfoViewsTests.swift

@@ -11,21 +11,18 @@ import XCTestExtensions
 
 
 final class PersonalInfoViewsTests: XCTestCase {
-    @MainActor
     override func setUpWithError() throws {
         try super.setUpWithError()
 
         continueAfterFailure = false
-
-        let app = XCUIApplication()
-        app.launch()
-
-        app.open(target: "SpeziPersonalInfo")
     }
 
     @MainActor
     func testNameFields() throws {
         let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziPersonalInfo")
 
         XCTAssert(app.buttons["Name Fields"].waitForExistence(timeout: 2))
         app.buttons["Name Fields"].tap()
@@ -43,6 +40,9 @@ final class PersonalInfoViewsTests: XCTestCase {
     @MainActor
     func testUserProfile() throws {
         let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziPersonalInfo")
 
         XCTAssert(app.buttons["User Profile"].waitForExistence(timeout: 2))
         app.buttons["User Profile"].tap()

Tests/UITests/TestAppUITests/SpeziValidation/ValidationTests.swift

@@ -11,21 +11,18 @@ import XCTestExtensions
 
 
 final class ValidationTests: XCTestCase {
-    @MainActor
     override func setUpWithError() throws {
         try super.setUpWithError()
 
         continueAfterFailure = false
-
-        let app = XCUIApplication()
-        app.launch()
-
-        app.open(target: "SpeziValidation")
     }
 
     @MainActor
     func testDefaultRules() {
         let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziValidation")
 
         XCTAssert(app.buttons["ValidationRules"].waitForExistence(timeout: 2))
         app.buttons["ValidationRules"].tap()
@@ -34,6 +31,8 @@ final class ValidationTests: XCTestCase {
     @MainActor
     func testValidationWithFocus() throws {
         let app = XCUIApplication()
+        app.launch()
+        app.open(target: "SpeziValidation")
 
         let passwordMessage = "Your password must be at least 8 characters long."
         let emptyMessage = "This field cannot be empty."
@@ -60,9 +59,7 @@ final class ValidationTests: XCTestCase {
         XCTAssertTrue(app.staticTexts[emptyMessage].exists)
 
 #if os(visionOS)
-        throw XCTSkip(
-            "This test is flakey on visionOS as the keyboard might be in front of the application and taps below will trigger keyboard buttons!"
-        )
+        throw XCTSkip("Test is flakey on visionOS as the keyboard might be in front of the application and taps below will trigger keyboard buttons!")
 #endif
 
         #if os(macOS)
@@ -100,4 +97,30 @@ final class ValidationTests: XCTestCase {
         XCTAssertTrue(app.textFields["Hello World!"].exists)
         XCTAssertTrue(app.textFields["Word"].exists)
     }
+
+    @MainActor
+    func testValidationPredicate() throws {
+        let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziValidation")
+
+        XCTAssert(app.buttons["Validation Picker"].waitForExistence(timeout: 2))
+        app.buttons["Validation Picker"].tap()
+
+        XCTAssertTrue(app.buttons["Cookies, Nothing selected"].waitForExistence(timeout: 2.0))
+        app.buttons["Cookies, Nothing selected"].tap()
+
+        XCTAssertTrue(app.buttons["Accept"].waitForExistence(timeout: 2.0))
+        app.buttons["Accept"].tap()
+
+        XCTAssertTrue(app.buttons["Cookies, Accept"].waitForExistence(timeout: 2.0))
+        app.buttons["Cookies, Accept"].tap()
+
+        XCTAssertTrue(app.buttons["Nothing selected"].waitForExistence(timeout: 2.0))
+        app.buttons["Nothing selected"].tap()
+
+        XCTAssertTrue(app.buttons["Cookies, Nothing selected"].waitForExistence(timeout: 2.0))
+        XCTAssertTrue(app.staticTexts["This field must be selected."].waitForExistence(timeout: 2.0))
+    }
 }

Tests/UITests/TestAppUITests/SpeziViews/EnvironmentTests.swift

@@ -11,22 +11,19 @@ import XCTestExtensions
 
 
 final class EnvironmentTests: XCTestCase {
-    @MainActor
     override func setUpWithError() throws {
         try super.setUpWithError()
 
         continueAfterFailure = false
+    }
 
+    @MainActor
+    func testDefaultErrorDescription() throws {
         let app = XCUIApplication()
         app.launch()
 
         app.open(target: "SpeziViews")
-    }
 
-    @MainActor
-    func testDefaultErrorDescription() throws {
-        let app = XCUIApplication()
-
 #if os(visionOS)
         app.buttons["View State"].swipeUp()
 #endif
@@ -36,15 +33,14 @@ final class EnvironmentTests: XCTestCase {
 
         XCTAssert(app.staticTexts["View State: processing"].waitForExistence(timeout: 2))
 
-        sleep(12)
-
 #if os(macOS)
         let alerts = app.sheets
 #else
         let alerts = app.alerts
 #endif
-        XCTAssert(alerts.staticTexts["This is a default error description!"].exists)
+        XCTAssert(alerts.staticTexts["This is a default error description!"].waitForExistence(timeout: 6.0))
         XCTAssert(alerts.staticTexts["Failure Reason\n\nHelp Anchor\n\nRecovery Suggestion"].exists)
+        XCTAssertTrue(alerts.buttons["OK"].exists)
         alerts.buttons["OK"].tap()
 
         XCTAssert(app.staticTexts["View State: idle"].waitForExistence(timeout: 2))

Tests/UITests/TestAppUITests/SpeziViews/ModelTests.swift

@@ -11,21 +11,18 @@ import XCTestExtensions
 
 
 final class ModelTests: XCTestCase {
-    @MainActor
     override func setUpWithError() throws {
         try super.setUpWithError()
 
         continueAfterFailure = false
-
-        let app = XCUIApplication()
-        app.launch()
-
-        app.open(target: "SpeziViews")
     }
 
     @MainActor
     func testViewState() throws {
         let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziViews")
 
         XCTAssert(app.buttons["View State"].waitForExistence(timeout: 2))
         app.buttons["View State"].tap()
@@ -50,6 +47,9 @@ final class ModelTests: XCTestCase {
     @MainActor
     func testOperationState() throws {
         let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziViews")
 
         XCTAssert(app.buttons["Operation State"].waitForExistence(timeout: 2))
         app.buttons["Operation State"].tap()
@@ -81,6 +81,9 @@ final class ModelTests: XCTestCase {
     @MainActor
     func testViewStateMapper() throws {
         let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziViews")
 
         XCTAssert(app.buttons["View State Mapper"].waitForExistence(timeout: 2))
         app.buttons["View State Mapper"].tap()
@@ -116,6 +119,9 @@ final class ModelTests: XCTestCase {
     @MainActor
     func testConditionalModifier() throws {
         let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziViews")
 
         XCTAssert(app.buttons["Conditional Modifier"].waitForExistence(timeout: 2))
         app.buttons["Conditional Modifier"].tap()
@@ -149,6 +155,9 @@ final class ModelTests: XCTestCase {
     @MainActor
     func testDefaultErrorDescription() throws {
         let app = XCUIApplication()
+        app.launch()
+
+        app.open(target: "SpeziViews")
 
         XCTAssert(app.buttons["Default Error Only"].waitForExistence(timeout: 2))
         app.buttons["Default Error Only"].tap()