Only enable diagnostics and fix settings change detection

src/Analysis/Engine/Test/LanguageServerTests.cs

@@ -28,6 +28,7 @@
 using Microsoft.Python.Tests.Utilities.FluentAssertions;
 using Microsoft.PythonTools;
 using Microsoft.PythonTools.Analysis;
+using Microsoft.PythonTools.Analysis.Analyzer;
 using Microsoft.PythonTools.Analysis.FluentAssertions;
 using Microsoft.PythonTools.Analysis.Infrastructure;
 using Microsoft.PythonTools.Interpreter;
@@ -340,6 +341,28 @@ public async Task ParseAndAnalysisDiagnostics() {
             );
         }
 
+        [TestMethod, Priority(0)]
+        public async Task DiagnosticsSettingChange() {
+            var diags = new Dictionary<Uri, PublishDiagnosticsEventArgs>();
+
+            using (var s = await CreateServer((Uri)null, null, diags)) {
+                var u = await s.OpenDefaultDocumentAndGetUriAsync("import foo\nx = y");
+
+                await s.WaitForCompleteAnalysisAsync(CancellationToken.None);
+                GetDiagnostics(diags, u).Should().OnlyContain(
+                    "Warning;Unable to resolve 'foo'. IntelliSense may be missing for this module.;Python (analysis);0;7;10",
+                    "Warning;unknown variable 'y';Python (analysis);1;4;5"
+                );
+
+                var newSettings = new ServerSettings();
+                newSettings.analysis.SetErrorSeverityOptions(Array.Empty<string>(), Array.Empty<string>(), Array.Empty<string>(), new[] { ErrorMessages.UsedBeforeAssignmentCode, ErrorMessages.UnresolvedImportCode });
+                await s.SendDidChangeConfiguration(newSettings);
+
+                await s.WaitForCompleteAnalysisAsync(CancellationToken.None);
+                GetDiagnostics(diags, u).Where(st => !st.StartsWith($"{DiagnosticSeverity.Unspecified}")).Should().BeEmpty();
+            }
+        }
+
         [TestMethod, Priority(0)]
         public async Task OnTypeFormattingLine() {
             using (var s = await CreateServer()) {

src/LanguageServer/Impl/Definitions/ServerSettings.cs

@@ -27,10 +27,10 @@ public class PythonAnalysisOptions {
             public int symbolsHierarchyDepthLimit = 10;
             public int symbolsHierarchyMaxSymbols = 1000;
 
-            public string[] errors { get; } = Array.Empty<string>();
-            public string[] warnings { get; } = Array.Empty<string>();
-            public string[] information { get; } = Array.Empty<string>();
-            public string[] disabled { get; } = Array.Empty<string>();
+            public string[] errors { get; private set; } = Array.Empty<string>();
+            public string[] warnings { get; private set; } = Array.Empty<string>();
+            public string[] information { get; private set; } = Array.Empty<string>();
+            public string[] disabled { get; private set; } = Array.Empty<string>();
 
             public DiagnosticSeverity GetEffectiveSeverity(string code, DiagnosticSeverity defaultSeverity)
                 => _map.TryGetValue(code, out var severity) ? severity : defaultSeverity;
@@ -50,6 +50,11 @@ public void SetErrorSeverityOptions(string[] errors, string[] warnings, string[]
                 foreach (var x in disabled) {
                     _map[x] = DiagnosticSeverity.Unspecified;
                 }
+
+                this.errors = errors;
+                this.warnings = warnings;
+                this.information = information;
+                this.disabled = disabled;
             }
         }
         public readonly PythonAnalysisOptions analysis = new PythonAnalysisOptions();

src/LanguageServer/Impl/Implementation/Server.cs

@@ -378,7 +378,7 @@ private async Task DoInitializeAsync(InitializeParams @params, CancellationToken
             _traceLogging = @params.initializationOptions.traceLogging;
             _analysisUpdates = @params.initializationOptions.analysisUpdates;
 
-            Analyzer.EnableDiagnostics = _clientCaps?.python?.liveLinting ?? false;
+            Analyzer.EnableDiagnostics = _clientCaps?.python?.liveLinting ?? true;
             _reloadModulesQueueItem = new ReloadModulesQueueItem(this);
 
             if (@params.initializationOptions.displayOptions != null) {

src/LanguageServer/Impl/LanguageServer.cs

@@ -421,7 +421,7 @@ private void PublishPendingDiagnostics() {
             foreach (var kvp in list) {
                 var parameters = new PublishDiagnosticsParams {
                     uri = kvp.Key,
-                    diagnostics = kvp.Value
+                    diagnostics = kvp.Value.Where(d => d.severity != DiagnosticSeverity.Unspecified).ToArray()
                 };
                 _rpc.NotifyWithParameterObjectAsync("textDocument/publishDiagnostics", parameters).DoNotWait();
             }