added tests to project

CursorLang.Tests/Models/AppSettingsTests.cs

@@ -0,0 +1,165 @@
+using System.ComponentModel;
+using System.Reflection;
+using System.Text.Json;
+using System.Windows.Media;
+using CursorLang.Models;
+
+namespace CursorLang.Tests.Models;
+
+public sealed class AppSettingsTests
+{
+    [Fact]
+    public void Default_values_describe_a_tooltip_at_the_cursor()
+    {
+        var settings = new AppSettings();
+
+        Assert.Equal("en", settings.Language);
+        Assert.Equal(AppTheme.System, settings.Theme);
+        Assert.Equal(PopupPlacementMode.AtCursor, settings.PlacementMode);
+        Assert.Equal(AnchorSide.BottomRight, settings.CursorSide);
+        Assert.Equal(16, settings.CursorOffset);
+        Assert.Equal(AnchorSide.BottomRight, settings.CaretSide);
+        Assert.Equal(16, settings.CaretOffset);
+        Assert.Equal(ScreenPosition.BottomRight, settings.ScreenPosition);
+        Assert.Equal(24, settings.ScreenMargin);
+        Assert.Equal(20, settings.FontSize);
+        Assert.Equal(0.9, settings.Opacity);
+        Assert.Equal(500, settings.DurationMilliseconds);
+        Assert.Equal(300, settings.CapsLockHoldMilliseconds);
+        Assert.Equal(Color.FromRgb(0x20, 0x20, 0x20), settings.BackgroundColor);
+        Assert.Equal(Color.FromRgb(0xFF, 0xFF, 0xFF), settings.ForegroundColor);
+    }
+
+    // The app must not change how the system behaves until it is asked to
+    [Fact]
+    public void Caps_Lock_interception_is_off_by_default()
+    {
+        Assert.False(new AppSettings().UseCapsLockHotkey);
+    }
+
+    [Fact]
+    public void The_time_on_screen_is_derived_from_milliseconds()
+    {
+        var settings = new AppSettings { DurationMilliseconds = 1250 };
+
+        Assert.Equal(TimeSpan.FromMilliseconds(1250), settings.Duration);
+    }
+
+    [Fact]
+    public void The_hold_threshold_is_derived_from_milliseconds()
+    {
+        var settings = new AppSettings { CapsLockHoldMilliseconds = 400 };
+
+        Assert.Equal(TimeSpan.FromMilliseconds(400), settings.CapsLockHoldDelay);
+    }
+
+    [Theory]
+    [MemberData(nameof(WritableProperties))]
+    public void A_changed_setting_is_announced_to_subscribers(string propertyName)
+    {
+        var settings = new AppSettings();
+        List<string?> changed = [];
+        settings.PropertyChanged += (_, e) => changed.Add(e.PropertyName);
+
+        SetDifferentValue(settings, propertyName);
+
+        Assert.Contains(propertyName, changed);
+    }
+
+    [Theory]
+    [MemberData(nameof(WritableProperties))]
+    public void Writing_the_same_value_leaves_subscribers_alone(string propertyName)
+    {
+        var settings = new AppSettings();
+        PropertyInfo property = typeof(AppSettings).GetProperty(propertyName)!;
+        object? value = property.GetValue(settings);
+
+        List<string?> changed = [];
+        settings.PropertyChanged += (_, e) => changed.Add(e.PropertyName);
+
+        property.SetValue(settings, value);
+
+        Assert.Empty(changed);
+    }
+
+    // Duration and CapsLockHoldDelay are derived from other settings and have
+    // no business being in the file
+    [Fact]
+    public void Derived_values_stay_out_of_the_file()
+    {
+        using JsonDocument document = JsonSerializer.SerializeToDocument(new AppSettings());
+
+        List<string> names = [.. document.RootElement.EnumerateObject().Select(property => property.Name)];
+
+        Assert.DoesNotContain(nameof(AppSettings.Duration), names);
+        Assert.DoesNotContain(nameof(AppSettings.CapsLockHoldDelay), names);
+
+        // What they are derived from, on the other hand, has to be stored
+        Assert.Contains(nameof(AppSettings.DurationMilliseconds), names);
+        Assert.Contains(nameof(AppSettings.CapsLockHoldMilliseconds), names);
+    }
+
+    [Fact]
+    public void Settings_report_changes_as_INotifyPropertyChanged()
+    {
+        Assert.IsAssignableFrom<INotifyPropertyChanged>(new AppSettings());
+    }
+
+    public static TheoryData<string> WritableProperties()
+    {
+        var data = new TheoryData<string>();
+
+        foreach (string name in WritablePropertyNames())
+        {
+            data.Add(name);
+        }
+
+        return data;
+    }
+
+    /// <summary>Names of the settings the user is able to change.</summary>
+    internal static IEnumerable<string> WritablePropertyNames() =>
+        typeof(AppSettings).GetProperties()
+            .Where(property => property.CanWrite)
+            .Select(property => property.Name);
+
+    // A value guaranteed to differ from the current one: each kind of setting
+    // has its own way of differing
+    private static void SetDifferentValue(AppSettings settings, string propertyName)
+    {
+        PropertyInfo property = typeof(AppSettings).GetProperty(propertyName)!;
+        object? current = property.GetValue(settings);
+
+        object next = current switch
+        {
+            string text => text + "-other",
+            double number => number + 1,
+            bool flag => !flag,
+            Color color => Color.FromRgb((byte)(color.R + 1), color.G, color.B),
+            Enum value => NextEnumValue(value),
+            DateTimeOffset moment => moment.AddDays(1),
+
+            // A setting never set yet: the app has not checked for updates once
+            null when property.PropertyType == typeof(DateTimeOffset?) => DateTimeOffset.UnixEpoch,
+
+            _ => throw new NotSupportedException($"Unknown kind of setting: {property.PropertyType}"),
+        };
+
+        property.SetValue(settings, next);
+    }
+
+    private static object NextEnumValue(Enum current)
+    {
+        Array values = Enum.GetValues(current.GetType());
+
+        foreach (object? value in values)
+        {
+            if (!Equals(value, current))
+            {
+                return value!;
+            }
+        }
+
+        throw new NotSupportedException($"{current.GetType()} has a single value");
+    }
+}

CursorLang.Tests/Models/KeyboardLayoutTests.cs

@@ -0,0 +1,76 @@
+using System.Globalization;
+using CursorLang.Models;
+
+namespace CursorLang.Tests.Models;
+
+public sealed class KeyboardLayoutTests
+{
+    [Theory]
+    [InlineData(0x0409, "EN")]
+    [InlineData(0x0419, "RU")]
+    [InlineData(0x040C, "FR")]
+    [InlineData(0x0407, "DE")]
+    public void The_short_name_comes_from_the_language_code(int localeId, string expected)
+    {
+        KeyboardLayout layout = KeyboardLayout.FromLocaleId(localeId);
+
+        Assert.Equal(expected, layout.ShortName);
+        Assert.Equal(localeId, layout.LocaleId);
+    }
+
+    [Fact]
+    public void The_full_name_joins_the_short_name_and_the_native_language_name()
+    {
+        KeyboardLayout layout = KeyboardLayout.FromLocaleId(0x0419);
+
+        Assert.Equal($"RU — {new CultureInfo(0x0419).NativeName}", layout.DisplayName);
+    }
+
+    // A layout may belong to a language the system does not know — that is not an error
+    [Fact]
+    public void An_unknown_locale_is_shown_by_its_own_code()
+    {
+        int unknown = FindUnknownLocaleId();
+
+        KeyboardLayout layout = KeyboardLayout.FromLocaleId(unknown);
+
+        string expected = $"0x{unknown:X4}";
+        Assert.Equal(expected, layout.ShortName);
+        Assert.Equal(expected, layout.DisplayName);
+    }
+
+    [Fact]
+    public void Layouts_of_the_same_locale_are_equal()
+    {
+        Assert.Equal(KeyboardLayout.FromLocaleId(0x0409), KeyboardLayout.FromLocaleId(0x0409));
+        Assert.NotEqual(KeyboardLayout.FromLocaleId(0x0409), KeyboardLayout.FromLocaleId(0x0419));
+    }
+
+    [Fact]
+    public void A_layout_can_also_be_built_directly()
+    {
+        var layout = new KeyboardLayout(1, "XX", "XX — language");
+
+        Assert.Equal(1, layout.LocaleId);
+        Assert.Equal("XX", layout.ShortName);
+        Assert.Equal("XX — language", layout.DisplayName);
+    }
+
+    // An identifier with no culture behind it in Windows
+    private static int FindUnknownLocaleId()
+    {
+        for (int candidate = 0x1000; candidate <= 0xFFFF; candidate++)
+        {
+            try
+            {
+                _ = new CultureInfo(candidate);
+            }
+            catch (CultureNotFoundException)
+            {
+                return candidate;
+            }
+        }
+
+        throw new InvalidOperationException("The system knows every locale identifier");
+    }
+}

CursorLang.Tests/Models/LayoutChangedEventArgsTests.cs

@@ -0,0 +1,27 @@
+using CursorLang.Models;
+
+namespace CursorLang.Tests.Models;
+
+public sealed class LayoutChangedEventArgsTests
+{
+    [Theory]
+    [InlineData(LayoutChangeReason.UserSwitched)]
+    [InlineData(LayoutChangeReason.ApplicationSwitched)]
+    public void The_event_carries_the_layout_and_the_reason(LayoutChangeReason reason)
+    {
+        KeyboardLayout layout = KeyboardLayout.FromLocaleId(0x0419);
+
+        var args = new LayoutChangedEventArgs(layout, reason);
+
+        Assert.Same(layout, args.Layout);
+        Assert.Equal(reason, args.Reason);
+    }
+
+    [Fact]
+    public void The_event_stays_an_ordinary_dotnet_event()
+    {
+        var args = new LayoutChangedEventArgs(KeyboardLayout.FromLocaleId(0x0409), LayoutChangeReason.UserSwitched);
+
+        Assert.IsAssignableFrom<EventArgs>(args);
+    }
+}