Add Dry-Run

.github/workflows/dotnet.yml

@@ -18,8 +18,11 @@ jobs:
       with:
         dotnet-version: 3.1.301
     - name: Restore dependencies
+      working-directory: src
       run: dotnet restore
     - name: Build
+      working-directory: src
       run: dotnet build --no-restore
     - name: Test
+      working-directory: src
       run: dotnet test --no-build --verbosity normal

src/MigrationEngine.Tests/MigrationEngine.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net472</TargetFramework>
+    <TargetFramework>netstandard21</TargetFramework>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 
@@ -15,4 +15,4 @@
     <ProjectReference Include="..\MigrationEngine\MigrationEngine.csproj" />
   </ItemGroup>
 
-</Project>
+</Project>

src/MigrationEngine/Implementations/DryRun/DryRunConnectionManager.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Data.Common;
+using System.Threading.Tasks;
+using MigrationEngine.Interfaces;
+
+namespace MigrationEngine.Implementations.DryRun
+{
+    public class DryRunConnectionManager : IConnectionManager
+    {
+        private readonly IConnectionManager manager;
+
+        public DryRunConnectionManager(IConnectionManager manager)
+        {
+            this.manager = manager;
+        }
+
+        public Task<T> RunCommand<T>(Func<DbCommand, Task<T>> action) => manager.RunCommand(action);
+
+        public void Commit()
+        {
+            // NEVER COMMIT IN A DRY RUN
+        }
+
+        public void Dispose()
+        {
+        }
+    }
+}

src/MigrationEngine/Implementations/DryRun/DryRunDatabase.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MigrationEngine.Interfaces;
+
+namespace MigrationEngine.Implementations.DryRun
+{
+    public class DryRunDatabase : IDatabase
+    {
+        public string Name { get; }
+
+        private readonly IConnectionManager connection;
+
+        public DryRunDatabase(string name, IConnectionManager connection)
+        {
+            Name = name;
+            this.connection = new DryRunConnectionManager(connection);
+        }
+
+        public Task Drop(CancellationToken token = default) => throw new Exception("Cannot drop in a dry run");
+
+        public Task<bool> Exists(CancellationToken token = default) => Task.FromResult(true);
+
+        public Task Create(CancellationToken token = default) => throw new Exception("Cannot create databases in a dry run");
+
+        public Task<IConnectionManager> OpenConnection(bool withTransaction = false) => Task.FromResult(connection);
+    }
+}

src/MigrationEngine/MigrationEngine.cs

@@ -26,19 +26,22 @@ public MigrationEngine(IDatabase database, ILogger log)
             this.log = log ?? NullLogger.Instance;
         }
 
-        public async Task EnsureDatabase(CancellationToken ct = default)
+        public async Task<TimeSpan> DryRun<T>(IEnumerable<IMigration<T>> migrations, IJournal<T> journal = null, CancellationToken ct = default)
+            where T : IJournalEntry
         {
-            if (!await database.Exists(ct))
+            using (var connection = await database.OpenConnection(true))
             {
-                await database.Create(ct);
+                return await MigrateInternal(new DryRunDatabase(database.Name, connection), migrations, journal, ct);
             }
         }
 
-        public Task<TimeSpan> Migrate<T>(IEnumerable<IMigration<T>> migrations, CancellationToken token = default)
+        public Task<TimeSpan> Migrate<T>(IEnumerable<IMigration<T>> migrations, IJournal<T> journal = null, CancellationToken ct = default)
             where T : IJournalEntry
-            => Migrate(migrations, new NullJournal<T>(), token);
+        {
+            return MigrateInternal(database, migrations, journal, ct);
+        }
 
-        public async Task<TimeSpan> Migrate<T>(IEnumerable<IMigration<T>> migrations, IJournal<T> journal = null, CancellationToken token = default)
+        private async Task<TimeSpan> MigrateInternal<T>(IDatabase db, IEnumerable<IMigration<T>> migrations, IJournal<T> journal, CancellationToken ct)
             where T : IJournalEntry
         {
             journal = journal ?? new NullJournal<T>();
@@ -52,11 +55,11 @@ public async Task<TimeSpan> Migrate<T>(IEnumerable<IMigration<T>> migrations, IJ
                 try
                 {
                     sw.Start();
-                    await mig.Run(database, journal, token);
+                    await mig.Run(db, journal, ct);
                     sw.Stop();
 
                     times[mig.Name] = sw.Elapsed;
-                    log.LogDebug("{0} ({1}) {2}", database.Name, sw.Elapsed, mig.Name);
+                    log.LogDebug("{0} ({1}) {2}", db.Name, sw.Elapsed, mig.Name);
 
                     sw.Reset();
                 }
@@ -71,12 +74,12 @@ public async Task<TimeSpan> Migrate<T>(IEnumerable<IMigration<T>> migrations, IJ
 
             async Task<IReadOnlyList<T>> EnsureJournal()
             {
-                using (var con = await database.OpenConnection())
+                using (var con = await db.OpenConnection())
                 {
-                    log.LogInformation("{0} -> Getting journal entries", database.Name);
-                    return await journal.EnsureJournal(con, token);
+                    log.LogInformation("{0} -> Getting journal entries", db.Name);
+                    return await journal.EnsureJournal(con, ct);
                 }
             }
         }
     }
-}
+}

src/MigrationEngine/MigrationEngine.csproj

@@ -4,7 +4,7 @@
   <PropertyGroup>
     <Title>MigrationEngine</Title>
     <Authors>pitermarx</Authors>
-    <TargetFrameworks>net472</TargetFrameworks>
+    <TargetFrameworks>netstandard21</TargetFrameworks>
     <AssemblyName>MigrationEngine</AssemblyName>
     <RootNamespace>MigrationEngine</RootNamespace>
     <PackageId>MigrationEngine</PackageId>