Merge pull request #1969 from cpraehaus/fix/gh-1960_version-track-dow…

…ngrades

Correctly handle version downgrades (e.g. via TestFlight)

DeviceTests/DeviceTests.Shared/VersionTracking_Tests.cs

@@ -0,0 +1,146 @@
+using System;
+using System.Diagnostics;
+using Xamarin.Essentials;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace DeviceTests
+{
+    public class VersionTracking_Tests
+    {
+        /// <summary>
+        /// We cannot mock the app version but it should be constant value
+        /// </summary>
+        const string currentVersion = "1.0.1.0";
+        const string currentBuild = "1";
+
+        const string versionTrailKey = "VersionTracking.Trail";
+        const string versionsKey = "VersionTracking.Versions";
+        const string buildsKey = "VersionTracking.Builds";
+        static readonly string sharedName = Preferences.GetPrivatePreferencesSharedName("versiontracking");
+
+        readonly ITestOutputHelper output;
+
+        public VersionTracking_Tests(ITestOutputHelper output)
+        {
+            this.output = output;
+        }
+
+        [Fact]
+        public void First_Launch_Ever()
+        {
+            VersionTracking.Track();
+            Preferences.Clear(sharedName);
+
+            VersionTracking.InitVersionTracking();
+
+            Assert.Equal(currentVersion, VersionTracking.CurrentVersion);
+            Assert.True(VersionTracking.IsFirstLaunchEver);
+            Assert.True(VersionTracking.IsFirstLaunchForCurrentVersion);
+            Assert.True(VersionTracking.IsFirstLaunchForCurrentBuild);
+        }
+
+        [Fact]
+        public void First_Launch_For_Version()
+        {
+            VersionTracking.Track();
+            Preferences.Set(versionsKey, string.Join("|", new string[] { "0.8.0", "0.9.0", "1.0.0" }), sharedName);
+            Preferences.Set(buildsKey, string.Join("|", new string[] { currentBuild }), sharedName);
+
+            VersionTracking.InitVersionTracking();
+
+            Assert.Equal(currentVersion, VersionTracking.CurrentVersion);
+            Assert.Equal("1.0.0", VersionTracking.PreviousVersion);
+            Assert.Equal("0.8.0", VersionTracking.FirstInstalledVersion);
+            Assert.False(VersionTracking.IsFirstLaunchEver);
+            Assert.True(VersionTracking.IsFirstLaunchForCurrentVersion);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentBuild);
+
+            VersionTracking.InitVersionTracking();
+
+            Assert.Equal(currentVersion, VersionTracking.CurrentVersion);
+            Assert.Equal("1.0.0", VersionTracking.PreviousVersion);
+            Assert.Equal("0.8.0", VersionTracking.FirstInstalledVersion);
+            Assert.False(VersionTracking.IsFirstLaunchEver);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentVersion);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentBuild);
+        }
+
+        [Fact]
+        public void First_Launch_For_Build()
+        {
+            VersionTracking.Track();
+            Preferences.Set(versionsKey, string.Join("|", new string[] { currentVersion }), sharedName);
+            Preferences.Set(buildsKey, string.Join("|", new string[] { "10", "20" }), sharedName);
+
+            VersionTracking.InitVersionTracking();
+
+            Assert.Equal(currentVersion, VersionTracking.CurrentVersion);
+            Assert.Equal("20", VersionTracking.PreviousBuild);
+            Assert.Equal("10", VersionTracking.FirstInstalledBuild);
+            Assert.False(VersionTracking.IsFirstLaunchEver);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentVersion);
+            Assert.True(VersionTracking.IsFirstLaunchForCurrentBuild);
+
+            VersionTracking.InitVersionTracking();
+
+            Assert.Equal(currentVersion, VersionTracking.CurrentVersion);
+            Assert.Equal("20", VersionTracking.PreviousBuild);
+            Assert.Equal("10", VersionTracking.FirstInstalledBuild);
+            Assert.False(VersionTracking.IsFirstLaunchEver);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentVersion);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentBuild);
+        }
+
+        [Fact]
+        public void First_Launch_After_Downgrade()
+        {
+            VersionTracking.Track();
+            Preferences.Set(versionsKey, string.Join("|", new string[] { currentVersion, "1.0.2", "1.0.3" }), sharedName);
+
+            VersionTracking.InitVersionTracking();
+            output.WriteLine(VersionTracking.GetStatus());
+
+            Assert.Equal(currentVersion, VersionTracking.CurrentVersion);
+            Assert.Equal("1.0.3", VersionTracking.PreviousVersion);
+            Assert.Equal("1.0.2", VersionTracking.FirstInstalledVersion);
+            Assert.False(VersionTracking.IsFirstLaunchEver);
+            Assert.True(VersionTracking.IsFirstLaunchForCurrentVersion);
+
+            VersionTracking.InitVersionTracking();
+
+            Assert.Equal(currentVersion, VersionTracking.CurrentVersion);
+            Assert.Equal("1.0.3", VersionTracking.PreviousVersion);
+            Assert.Equal("1.0.2", VersionTracking.FirstInstalledVersion);
+            Assert.False(VersionTracking.IsFirstLaunchEver);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentVersion);
+        }
+
+        [Fact]
+        public void First_Launch_After_Build_Downgrade()
+        {
+            VersionTracking.Track();
+            Preferences.Set(versionsKey, string.Join("|", new string[] { currentVersion }), sharedName);
+            Preferences.Set(buildsKey, string.Join("|", new string[] { currentBuild, "10", "20" }), sharedName);
+
+            VersionTracking.InitVersionTracking();
+            output.WriteLine(VersionTracking.GetStatus());
+
+            Assert.Equal(currentBuild, VersionTracking.CurrentBuild);
+            Assert.Equal("20", VersionTracking.PreviousBuild);
+            Assert.Equal("10", VersionTracking.FirstInstalledBuild);
+            Assert.False(VersionTracking.IsFirstLaunchEver);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentVersion);
+            Assert.True(VersionTracking.IsFirstLaunchForCurrentBuild);
+
+            VersionTracking.InitVersionTracking();
+
+            Assert.Equal(currentBuild, VersionTracking.CurrentBuild);
+            Assert.Equal("20", VersionTracking.PreviousBuild);
+            Assert.Equal("10", VersionTracking.FirstInstalledBuild);
+            Assert.False(VersionTracking.IsFirstLaunchEver);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentVersion);
+            Assert.False(VersionTracking.IsFirstLaunchForCurrentBuild);
+        }
+    }
+}

Xamarin.Essentials/VersionTracking/VersionTracking.shared.cs

@@ -13,9 +13,20 @@ public static class VersionTracking
 
         static readonly string sharedName = Preferences.GetPrivatePreferencesSharedName("versiontracking");
 
-        static readonly Dictionary<string, List<string>> versionTrail;
+        static Dictionary<string, List<string>> versionTrail;
 
         static VersionTracking()
+        {
+            InitVersionTracking();
+        }
+
+        /// <summary>
+        /// Initialize VersionTracking module, load data and track current version
+        /// </summary>
+        /// <remarks>
+        /// For internal use. Usually only called once in production code, but multiple times in unit tests
+        /// </remarks>
+        internal static void InitVersionTracking()
         {
             IsFirstLaunchEver = !Preferences.ContainsKey(versionsKey, sharedName) || !Preferences.ContainsKey(buildsKey, sharedName);
             if (IsFirstLaunchEver)
@@ -35,15 +46,19 @@ static VersionTracking()
                 };
             }
 
-            IsFirstLaunchForCurrentVersion = !versionTrail[versionsKey].Contains(CurrentVersion);
+            IsFirstLaunchForCurrentVersion = !versionTrail[versionsKey].Contains(CurrentVersion) || CurrentVersion != LastInstalledVersion;
             if (IsFirstLaunchForCurrentVersion)
             {
+                // Avoid duplicates and move current version to end of list if already present
+                versionTrail[versionsKey].RemoveAll(v => v == CurrentVersion);
                 versionTrail[versionsKey].Add(CurrentVersion);
             }
 
-            IsFirstLaunchForCurrentBuild = !versionTrail[buildsKey].Contains(CurrentBuild);
+            IsFirstLaunchForCurrentBuild = !versionTrail[buildsKey].Contains(CurrentBuild) || CurrentBuild != LastInstalledBuild;
             if (IsFirstLaunchForCurrentBuild)
             {
+                // Avoid duplicates and move current build to end of list if already present
+                versionTrail[buildsKey].RemoveAll(b => b == CurrentBuild);
                 versionTrail[buildsKey].Add(CurrentBuild);
             }
 
@@ -119,5 +134,9 @@ static string GetPrevious(string key)
             var trail = versionTrail[key];
             return (trail.Count >= 2) ? trail[trail.Count - 2] : null;
         }
+
+        static string LastInstalledVersion => versionTrail[versionsKey].LastOrDefault();
+
+        static string LastInstalledBuild => versionTrail[buildsKey].LastOrDefault();
     }
 }