Npgsql: Fix test cases to use async, stop relevant warnings

Author: amotl

by-language/csharp-npgsql/DemoProgram.cs

@@ -18,51 +18,47 @@ await Parser.Default.ParseArguments<Options>(args)
                     var connString = $"Host={options.Host};Port={options.Port};SSL Mode={options.SslMode};" +
                                      $"Username={options.Username};Password={options.Password};Database={options.Database}";
                     Console.WriteLine($"Connecting to {connString}\n");
-                    using (var conn = new NpgsqlConnection(connString))
-                    {
-                        conn.Open();
-                        var program = new DatabaseWorkloads();
-                        await program.SystemQueryExample(conn);
-                        await program.BasicConversationExample(conn);
-                        await program.AsyncUnnestExample(conn);
-                        conn.Close();
-                    }
-
+                    await using var conn = new NpgsqlConnection(connString);
+                    conn.Open();
+                    await DatabaseWorkloads.SystemQueryExample(conn);
+                    await DatabaseWorkloads.BasicConversationExample(conn);
+                    await DatabaseWorkloads.UnnestExample(conn);
+                    conn.Close();
                 });
 
         }
 
         public class Options
         {
             [Option('h', "host", Required = false, HelpText = "Host name to connect to", Default = "localhost")]
-            public string Host { get; set; }
+            public string? Host { get; set; }
 
             [Option('p', "port", Required = false, HelpText = "Port number to connect to", Default = 5432)]
             public int Port { get; set; }
 
             // Controls whether SSL is used, depending on server support. Can be Require, Disable, or Prefer.
             // https://www.npgsql.org/doc/connection-string-parameters.html#security-and-encryption
             [Option('s', "ssl-mode", Required = false, HelpText = "Which SSL mode to use", Default = "Disable")]
-            public string SslMode { get; set; }
+            public string? SslMode { get; set; }
 
             [Option('u', "username", Required = false, HelpText = "Username to authenticate with", Default = "crate")]
-            public string Username { get; set; }
+            public string? Username { get; set; }
             [Option('w', "password", Required = false, HelpText = "Password to authenticate with", Default = "")]
-            public string Password { get; set; }
+            public string? Password { get; set; }
             [Option('d', "database", Required = false, HelpText = "Database to use", Default = "testdrive")]
-            public string Database { get; set; }
+            public string? Database { get; set; }
         }
 
     }
 
     public class DatabaseWorkloads
     {
-        public async Task<List<string>> SystemQueryExample(NpgsqlConnection conn)
+        public static async Task<List<string>> SystemQueryExample(NpgsqlConnection conn)
         {
             Console.WriteLine("Running SystemQueryExample");
             var mountains = new List<string>();
-            using (var cmd = new NpgsqlCommand("SELECT mountain FROM sys.summits ORDER BY 1 LIMIT 25", conn))
-            using (var reader = cmd.ExecuteReader())
+            await using (var cmd = new NpgsqlCommand("SELECT mountain FROM sys.summits ORDER BY 1 LIMIT 25", conn))
+            await using (var reader = cmd.ExecuteReader())
             {
                 while (await reader.ReadAsync())
                 {
@@ -76,31 +72,32 @@ public async Task<List<string>> SystemQueryExample(NpgsqlConnection conn)
             return mountains;
         }
 
-        public async Task<List<int>> BasicConversationExample(NpgsqlConnection conn)
+        public static async Task<List<int>> BasicConversationExample(NpgsqlConnection conn)
         {
             Console.WriteLine("Running BasicConversationExample");
 
             // Submit DDL, create database schema.
-            using (var cmd = new NpgsqlCommand("DROP TABLE IF EXISTS testdrive.basic", conn))
+            await using (var cmd = new NpgsqlCommand("DROP TABLE IF EXISTS testdrive.basic", conn))
             {
                 cmd.ExecuteNonQuery();
             }
-            using (var cmd = new NpgsqlCommand("CREATE TABLE testdrive.basic (x int)", conn))
+
+            await using (var cmd = new NpgsqlCommand("CREATE TABLE testdrive.basic (x int)", conn))
             {
                 cmd.ExecuteNonQuery();
             }
 
             // Insert single data point.
-            using (var cmd = new NpgsqlCommand("INSERT INTO testdrive.basic (x) VALUES (@x)", conn))
+            await using (var cmd = new NpgsqlCommand("INSERT INTO testdrive.basic (x) VALUES (@x)", conn))
             {
                 cmd.Parameters.AddWithValue("x", -999);
                 cmd.ExecuteNonQuery();
             }
 
             // Insert multiple data points.
-            using (var cmd = new NpgsqlCommand("INSERT INTO testdrive.basic (x) VALUES (@x)", conn))
+            await using (var cmd = new NpgsqlCommand("INSERT INTO testdrive.basic (x) VALUES (@x)", conn))
             {
-                using (var transaction = conn.BeginTransaction())
+                await using (var transaction = conn.BeginTransaction())
                 {
                     cmd.Transaction = transaction;
                     cmd.Parameters.Add("@x", NpgsqlDbType.Integer);
@@ -116,15 +113,15 @@ public async Task<List<int>> BasicConversationExample(NpgsqlConnection conn)
             }
 
             // Flush data.
-            using (var cmd = new NpgsqlCommand("REFRESH TABLE testdrive.basic", conn))
+            await using (var cmd = new NpgsqlCommand("REFRESH TABLE testdrive.basic", conn))
             {
                 cmd.ExecuteNonQuery();
             }
 
             // Query back data.
             var data = new List<int>();
-            using (var cmd = new NpgsqlCommand("SELECT x FROM testdrive.basic ORDER BY 1 ASC LIMIT 10", conn))
-            using (var reader = cmd.ExecuteReader())
+            await using (var cmd = new NpgsqlCommand("SELECT x FROM testdrive.basic ORDER BY 1 ASC LIMIT 10", conn))
+            await using (var reader = cmd.ExecuteReader())
             {
                 while (await reader.ReadAsync())
                 {
@@ -139,20 +136,20 @@ public async Task<List<int>> BasicConversationExample(NpgsqlConnection conn)
             return data;
         }
 
-        public async Task<int> AsyncUnnestExample(NpgsqlConnection conn)
+        public static async Task<int> UnnestExample(NpgsqlConnection conn)
         {
             Console.WriteLine("Running AsyncUnnestExample");
 
             // Submit DDL, create database schema.
-            using (var cmd = new NpgsqlCommand("DROP TABLE IF EXISTS testdrive.unnest", conn))
+            await using (var cmd = new NpgsqlCommand("DROP TABLE IF EXISTS testdrive.unnest", conn))
             {
                 await cmd.ExecuteNonQueryAsync();
             }
 
-            using (var cmd2 = new NpgsqlCommand(
-                connection: conn,
-                cmdText: "CREATE TABLE IF NOT EXISTS testdrive.unnest (id int, name text)"
-            ))
+            await using (var cmd2 = new NpgsqlCommand(
+                             connection: conn,
+                             cmdText: "CREATE TABLE IF NOT EXISTS testdrive.unnest (id int, name text)"
+                         ))
             {
                 await cmd2.ExecuteNonQueryAsync();
             }
@@ -170,16 +167,16 @@ public async Task<int> AsyncUnnestExample(NpgsqlConnection conn)
             await cmd3.ExecuteNonQueryAsync();
 
             // Flush data.
-            using (var cmd = new NpgsqlCommand("REFRESH TABLE testdrive.unnest", conn))
+            await using (var cmd = new NpgsqlCommand("REFRESH TABLE testdrive.unnest", conn))
             {
                 cmd.ExecuteNonQuery();
             }
 
             // Query back data.
             var resultCount = -1;
-            using (var cmd = new NpgsqlCommand("SELECT COUNT(*) FROM testdrive.unnest", conn))
+            await using (var cmd = new NpgsqlCommand("SELECT COUNT(*) FROM testdrive.unnest", conn))
             {
-                using (var reader = cmd.ExecuteReader())
+                await using (var reader = cmd.ExecuteReader())
                 {
                     await reader.ReadAsync();
                     resultCount = reader.GetInt32(0);

by-language/csharp-npgsql/README.rst

@@ -66,6 +66,10 @@ For running the tests against a remote database, use, for example::
     export CRATEDB_DSN='Host=clustername.aks1.westeurope.azure.cratedb.net;Port=5432;SSL Mode=Require;Username=foobar;Password=X8F%Shn)TESTvF5ac7%eW4NM;Database=testdrive'
     dotnet test --framework=net8.0
 
+For running tests selectively, use::
+
+    dotnet test --framework=net8.0 --filter SystemQueryExample
+
 
 .. _C#: https://en.wikipedia.org/wiki/C_Sharp_(programming_language)
 .. _crate-npgsql: https://github.com/crate/crate-npgsql

by-language/csharp-npgsql/demo.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <IsPackable>false</IsPackable>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <GenerateProgramFile>false</GenerateProgramFile>

by-language/csharp-npgsql/tests/DemoProgramTest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Threading.Tasks;
 using Npgsql;
 using Xunit;
 
@@ -41,44 +42,41 @@ public DemoProgramTest(DatabaseFixture fixture)
         }
 
         [Fact]
-        public void TestSystemQueryExample()
+        public async Task TestSystemQueryExample()
         {
             var conn = fixture.Db;
 
             // Invoke database workload.
-            var task = program.SystemQueryExample(conn);
-            task.Wait();
+            var task = DatabaseWorkloads.SystemQueryExample(conn);
+            var mountains = await task.WaitAsync(TimeSpan.FromSeconds(0.5));
 
             // Check results.
-            var mountains = task.Result;
             Assert.Equal("Acherkogel", mountains[0]);
         }
 
         [Fact]
-        public void TestBasicConversationExample()
+        public async Task TestBasicConversationExample()
         {
             var conn = fixture.Db;
 
             // Invoke database workload.
-            var task = program.BasicConversationExample(conn);
-            task.Wait();
+            var task = DatabaseWorkloads.BasicConversationExample(conn);
+            var results = await task.WaitAsync(TimeSpan.FromSeconds(0.5));
 
             // Check results.
-            var results = task.Result;
             Assert.Equal(new List<int>() { -999, 10, 20, 30, 40, 50, 60, 70, 80, 90 }, results);
         }
 
         [Fact]
-        public void TestAsyncUnnestExample()
+        public async Task TestUnnestExample()
         {
             var conn = fixture.Db;
 
             // Invoke database workload.
-            var task = program.AsyncUnnestExample(conn);
-            task.Wait();
+            var task = DatabaseWorkloads.UnnestExample(conn);
+            var resultCount = await task.WaitAsync(TimeSpan.FromSeconds(0.5));
 
             // Check results.
-            var resultCount = task.Result;
             Assert.Equal(10, resultCount);
         }