fix(notification): save smtp sender without reentering password

Preserve the saved SMTP password when connection settings are unchanged and keep it out of admin forms.

Ref: IT-1601

HrynCo.NotificationService.Web.IntegrationTests/AdminSmtpSaveTests.cs

@@ -0,0 +1,136 @@
+using System.Net;
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+using HrynCo.NotificationService.DAL.Abstract.Repositories;
+using HrynCo.NotificationService.DAL.EF;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace HrynCo.NotificationService.Web.IntegrationTests;
+
+public sealed class AdminSmtpSaveTests(TemplateDatabaseFixture fixture) : IClassFixture<TemplateDatabaseFixture>
+{
+    [Fact]
+    public async Task BlankPasswordKeepsSavedValueWhenOnlySenderChanges()
+    {
+        await using var context = await DefinitionApiTestContext.CreateAsync(fixture);
+        var channel = await SeedChannel(context);
+        using var client = context.App.CreateClient(new() { AllowAutoRedirect = false });
+        var fields = TemplateEditorTestFields.Read(await client.GetStringAsync($"/admin/channels/{channel.Id}"));
+        fields["UseSsl"] = "true";
+        fields["Password"] = "";
+        fields["FromName"] = "Updated sender";
+
+        var response = await client.PostAsync("/admin/channels/save", new FormUrlEncodedContent(fields));
+
+        Assert.Equal(HttpStatusCode.Redirect, response.StatusCode);
+        var saved = await ReadSettings(context, channel.Id);
+        Assert.Equal("saved-test-secret", saved.Password);
+        Assert.Equal("Updated sender", saved.FromName);
+    }
+
+    [Theory]
+    [InlineData("Host", "other.example.invalid")]
+    [InlineData("Port", "2525")]
+    [InlineData("Username", "other-user")]
+    [InlineData("UseSsl", "false")]
+    public async Task ChangedConnectionWithBlankPasswordIsRejected(string field, string value)
+    {
+        await using var context = await DefinitionApiTestContext.CreateAsync(fixture);
+        var channel = await SeedChannel(context);
+        using var client = context.App.CreateClient(new() { AllowAutoRedirect = false });
+        var fields = TemplateEditorTestFields.Read(await client.GetStringAsync($"/admin/channels/{channel.Id}"));
+        fields["UseSsl"] = "true";
+        fields["Password"] = "";
+        fields[field] = value;
+
+        var response = await client.PostAsync("/admin/channels/save", new FormUrlEncodedContent(fields));
+        var html = await response.Content.ReadAsStringAsync();
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        Assert.Contains("Enter the password to save changed SMTP connection settings.", html);
+        Assert.DoesNotContain("saved-test-secret", html);
+        var saved = await ReadSettings(context, channel.Id);
+        Assert.Equal("saved-test-secret", saved.Password);
+        Assert.Equal("smtp.example.invalid", saved.Host);
+    }
+
+    [Fact]
+    public async Task ExplicitPasswordCanReplaceSavedValue()
+    {
+        await using var context = await DefinitionApiTestContext.CreateAsync(fixture);
+        var channel = await SeedChannel(context);
+        using var client = context.App.CreateClient(new() { AllowAutoRedirect = false });
+        var fields = TemplateEditorTestFields.Read(await client.GetStringAsync($"/admin/channels/{channel.Id}"));
+        fields["UseSsl"] = "true";
+        fields["Password"] = "replacement-test-secret";
+        fields["Host"] = "other.example.invalid";
+
+        var response = await client.PostAsync("/admin/channels/save", new FormUrlEncodedContent(fields));
+
+        Assert.Equal(HttpStatusCode.Redirect, response.StatusCode);
+        var saved = await ReadSettings(context, channel.Id);
+        Assert.Equal("replacement-test-secret", saved.Password);
+        Assert.Equal("other.example.invalid", saved.Host);
+    }
+
+    [Fact]
+    public async Task NewChannelStillRequiresPassword()
+    {
+        await using var context = await DefinitionApiTestContext.CreateAsync(fixture);
+        using var client = context.App.CreateClient(new() { AllowAutoRedirect = false });
+        var fields = TemplateEditorTestFields.Read(await client.GetStringAsync("/admin/channels/create"));
+        fields["ServiceName"] = "NewTestService";
+        fields["Host"] = "smtp.example.invalid";
+        fields["Username"] = "test-user";
+        fields["FromEmail"] = "sender@example.invalid";
+        fields["FromName"] = "Sender";
+        fields["Password"] = "";
+
+        var response = await client.PostAsync("/admin/channels/save", new FormUrlEncodedContent(fields));
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        Assert.Contains("The Password field is required.", await response.Content.ReadAsStringAsync());
+    }
+
+    [Fact]
+    public async Task InvalidFormDoesNotRenderEnteredPassword()
+    {
+        await using var context = await DefinitionApiTestContext.CreateAsync(fixture);
+        var channel = await SeedChannel(context);
+        using var client = context.App.CreateClient(new() { AllowAutoRedirect = false });
+        var fields = TemplateEditorTestFields.Read(await client.GetStringAsync($"/admin/channels/{channel.Id}"));
+        fields["Password"] = "replacement-test-secret";
+        fields["FromEmail"] = "invalid-address";
+
+        var response = await client.PostAsync("/admin/channels/save", new FormUrlEncodedContent(fields));
+        var html = await response.Content.ReadAsStringAsync();
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        Assert.DoesNotContain("replacement-test-secret", html);
+        Assert.Equal("saved-test-secret", (await ReadSettings(context, channel.Id)).Password);
+    }
+
+    private static async Task<EmailChannel> SeedChannel(DefinitionApiTestContext context)
+    {
+        using var scope = context.App.Services.CreateScope();
+        var channel = new EmailChannel
+        {
+            ServiceName = "TestService", EmailChannelType = EmailChannelType.Smtp,
+            Settings = new SmtpChannelSettings
+            {
+                Host = "smtp.example.invalid", Port = 587, Username = "test-user",
+                Password = "saved-test-secret", UseSsl = true,
+                FromEmail = "sender@example.invalid", FromName = "Original sender"
+            }
+        };
+        await scope.ServiceProvider.GetRequiredService<IEmailChannelRepository>().AddAsync(channel);
+        await scope.ServiceProvider.GetRequiredService<NotificationDbContext>().SaveChangesAsync();
+        return channel;
+    }
+
+    private static async Task<SmtpChannelSettings> ReadSettings(DefinitionApiTestContext context, Guid id)
+    {
+        using var scope = context.App.Services.CreateScope();
+        var channel = await scope.ServiceProvider.GetRequiredService<IEmailChannelRepository>().GetByIdAsync(id);
+        return Assert.IsType<SmtpChannelSettings>(channel?.Settings);
+    }
+}