Add support for default values in single choice questions in survey

Default values weren't selected automatically in surveys that showed a single
option. With this change, a new `defaultOption` is added to the survey and used
in case the selected value is not there. Now this works as it should, and how
it works in Android.

The reason why a default option was added and the default value is not just set
as the selected one, is because the question view starts with props, and the
prop is either selected or not. However, the question view wouldn't know if an
option is selected because of user input or because of the default value. If the
view is selected because of user input, then `opt.select(opt)` needs to be
executed only on user interaction, but in case of default value, it needs to be
run automatically as soon as the view is presented. I don't know how to make
this distinction without having the default value separately.

Also, a snapshot test was added to ensure that when there's a default value,
it's selected correctly.

MOB-2747

GliaWidgets/Sources/ViewController/Survey/Components/SingleChoiceQuestionView/Survey.SingleChoiceQuestionView.swift

@@ -85,16 +85,35 @@ extension Survey {
             zip(props.options, optionsStack.arrangedSubviews)
                 .forEach { opt, view in
                     guard let checkboxView = view as? CheckboxView else { return }
+
+                    let state = Self.handleSelection(with: props, option: opt)
+
                     checkboxView.props = .init(
                         title: opt.name,
-                        state: props.selected == opt ? .selected : .active
+                        state: state
                     ) {
                         opt.select(opt)
                     }
                 }
             validationError.isHidden = !props.showValidationError
         }
 
+        static func handleSelection(
+            with props: Props,
+            option opt: Survey.Option<String>
+        ) -> CheckboxView.State {
+            // If user selected or it should be selected by default.
+            let isSelected = props.selected == opt || props.defaultOption == opt
+
+            // Trigger selection manually because the option has
+            // been selected by default, not because of user input.
+            if isSelected, props.selected == nil {
+                opt.select(opt)
+            }
+
+            return isSelected ? .selected : .active
+        }
+
         // MARK: - Private
 
         private let style: Theme.SurveyStyle.SingleQuestion
@@ -109,6 +128,7 @@ extension Survey.SingleChoiceQuestionView {
         var showValidationError: Bool
         var options: [Survey.Option<String>]
         var selected: Survey.Option<String>?
+        var defaultOption: Survey.Option<String>?
         var answerContainer: CoreSdkClient.SurveyAnswerContainer?
         let accessibility: Accessibility
 
@@ -124,6 +144,7 @@ extension Survey.SingleChoiceQuestionView {
             showValidationError: Bool = false,
             options: [Survey.Option<String>] = [],
             selected: Survey.Option<String>? = nil,
+            defaultOption: Survey.Option<String>? = nil,
             answerContainer: CoreSdkClient.SurveyAnswerContainer? = nil,
             accessibility: Accessibility
         ) {
@@ -133,6 +154,7 @@ extension Survey.SingleChoiceQuestionView {
             self.showValidationError = showValidationError
             self.options = options
             self.selected = selected
+            self.defaultOption = defaultOption
             self.answerContainer = answerContainer
             self.accessibility = accessibility
         }

GliaWidgets/Sources/ViewController/Survey/Mocks/Survey.ViewController.Props.Mock.swift

@@ -16,6 +16,23 @@ extension Survey.ViewController.Props {
         )
     }
 
+    static func emptyPropsMockWithDefaultValue() -> Survey.ViewController.Props {
+        return Survey.ViewController.Props(
+            header: "Survey title",
+            props: [
+                makeScalePropsMock(),
+                makeInputPropsMock(),
+                makeBooleanPropsMock(),
+                makeSinglePropsMock(defaultOption: .init(
+                    name: "Second option",
+                    value: "\(2)"
+                ))
+            ],
+            submit: { _ in },
+            cancel: {}
+        )
+    }
+
     static func filledPropsMock() -> Survey.ViewController.Props {
         return Survey.ViewController.Props(
             header: "Survey title",
@@ -99,6 +116,7 @@ private extension Survey.ViewController.Props {
 
     static func makeSinglePropsMock(
         selectedOption: Survey.Option<String>? = nil,
+        defaultOption: Survey.Option<String>? = nil,
         showValidationError: Bool = false
     ) -> Survey.SingleChoiceQuestionView.Props {
         var props = Survey.SingleChoiceQuestionView.Props(
@@ -113,6 +131,7 @@ private extension Survey.ViewController.Props {
             .init(name: "Second option", value: "\(2)"),
             .init(name: "Third option", value: "\(3)")
         ].compactMap { $0 }
+        props.defaultOption = defaultOption
         props.selected = selectedOption
         return props
     }

GliaWidgets/Sources/ViewController/Survey/Survey.ViewController.Props.swift

@@ -203,10 +203,24 @@ extension Survey.ViewController.Props {
         ? Localization.Survey.Question.Required.Accessibility.label
         : nil
 
+        let defaultOption: Survey.Option<String>? = {
+            let defaultOption = sdkQuestion.options?.first {
+                $0.isDefault == true
+            }
+
+            guard let defaultOption else { return nil }
+
+            return .init(
+                name: defaultOption.label,
+                value: defaultOption.id.rawValue
+            )
+        }()
+
         var scaleProps = Survey.SingleChoiceQuestionView.Props(
             id: sdkQuestion.id.rawValue,
             title: sdkQuestion.text,
             isRequired: sdkQuestion.required,
+            defaultOption: defaultOption,
             accessibility: .init(value: accessibilityValue)
         )
         let handleSingleOptionSelection = { (option: Survey.Option<String>) in

GliaWidgetsTests/Sources/Survey.SingleChouceQuestionViewTests.swift

@@ -0,0 +1,92 @@
+import Foundation
+import XCTest
+@testable import GliaWidgets
+
+final class SurveySingleChoiceQuestionViewTests: XCTestCase {
+    static let firstOption = Survey.Option(name: "Option 1", value: "1")
+    static let secondOption = Survey.Option(name: "Option 2", value: "2")
+
+    var props: Survey.SingleChoiceQuestionView.Props = {
+        var props = Survey.SingleChoiceQuestionView.Props(
+            id: "1",
+            title: "Survey",
+            isRequired: true,
+            accessibility: .init(value: "")
+        )
+        props.options = [
+            firstOption,
+            secondOption
+        ]
+        return props
+    }()
+
+    func test_regularOptionIsActive() {
+        let regularOption = Self.firstOption
+
+        let selection = Survey.SingleChoiceQuestionView.handleSelection(
+            with: props,
+            option: regularOption
+        )
+
+        XCTAssertEqual(selection, .active)
+    }
+
+    func test_defaultOptionIsSelected() {
+        var hasSelectedDefaultOption = false
+
+        let defaultOption = Survey.Option<String>(
+            name: "Option 1",
+            value: "1",
+            select: { _ in
+                hasSelectedDefaultOption = true
+            }
+        )
+
+        props.defaultOption = defaultOption
+        props.options = [defaultOption, Self.secondOption]
+
+        let selection = Survey.SingleChoiceQuestionView.handleSelection(
+            with: props,
+            option: defaultOption
+        )
+
+        XCTAssertEqual(selection, .selected)
+        XCTAssertEqual(hasSelectedDefaultOption, true)
+    }
+
+    func test_regularOptionIsActiveWhenDefaultIsPresent() {
+        let defaultOption = Self.firstOption
+        props.defaultOption = defaultOption
+
+        let selection = Survey.SingleChoiceQuestionView.handleSelection(
+            with: props,
+            option: Self.secondOption
+        )
+
+        XCTAssertEqual(selection, .active)
+    }
+
+    func test_selectedOptionIsSelected() {
+        let selectedOption = Self.firstOption
+        props.selected = selectedOption
+
+        let selection = Survey.SingleChoiceQuestionView.handleSelection(
+            with: props,
+            option: selectedOption
+        )
+
+        XCTAssertEqual(selection, .selected)
+    }
+
+    func test_regularOptionIsActiveWhenSelectedIsPresent() {
+        let selectedOption = Self.firstOption
+        props.selected = selectedOption
+
+        let selection = Survey.SingleChoiceQuestionView.handleSelection(
+            with: props,
+            option: Self.secondOption
+        )
+
+        XCTAssertEqual(selection, .active)
+    }
+}

SnapshotTests/SurveyViewControllerVoiceOverTests.swift

@@ -13,6 +13,15 @@ final class SurveyViewControllerVoiceOverTests: SnapshotTestCase {
         viewController.assertSnapshot(as: .accessibilityImage)
     }
 
+    func test_emptySurveyWithDefaultValue() {
+        let viewController = Survey.ViewController(
+            viewFactory: .mock(),
+            environment: .init(notificationCenter: .mock),
+            props: .emptyPropsMockWithDefaultValue()
+        )
+        viewController.assertSnapshot(as: .accessibilityImage)
+    }
+
     func test_filledSurvey() {
         let viewController = Survey.ViewController(
             viewFactory: .mock(),