Tests for disabling rules

Author: jaredpar

src/Microsoft.DotNet.CodeFormatting.Tests/Rules/CombinationTest.cs

@@ -10,13 +10,14 @@
 using Microsoft.CodeAnalysis;
 using Xunit;
 using System.Collections.Immutable;
+using Microsoft.DotNet.CodeFormatting.Rules;
 
 namespace Microsoft.DotNet.CodeFormatting.Tests
 {
     /// <summary>
     /// A test which runs all rules on a given piece of code 
     /// </summary>
-    public sealed class CombinationTest : CodeFormattingTestBase, IDisposable
+    public sealed class CombinationTest : CodeFormattingTestBase
     {
         private FormattingEngineImplementation _formattingEngine;
 
@@ -29,9 +30,18 @@ public CombinationTest()
             _formattingEngine.PreprocessorConfigurations = ImmutableArray<string[]>.Empty;
         }
 
-        public void Dispose()
+        private void DisableAllRules()
         {
-            _formattingEngine.AllowTables = false;
+            foreach (var rule in _formattingEngine.AllRules)
+            {
+                _formattingEngine.ToggleRuleEnabled(rule, enabled: false);
+            }
+        }
+
+        private void ToggleRule(string name, bool enabled)
+        {
+            var rule = _formattingEngine.AllRules.Where(x => x.Name == name).Single();
+            _formattingEngine.ToggleRuleEnabled(rule, enabled);
         }
 
         protected override async Task<Document> RewriteDocumentAsync(Document document)
@@ -70,6 +80,64 @@ private void M()
             Verify(text, expected, runFormatter: false);
         }
 
+        /// <summary>
+        /// Ensure the engine respects the rule map
+        /// </summary>
+        [Fact]
+        public void FieldOnly()
+        {
+            var text = @"
+class C {
+    int field;
+
+    void M() {
+        N(this.field);
+    }
+}";
+
+            var expected = @"
+class C {
+    int _field;
+
+    void M() {
+        N(this._field);
+    }
+}";
+
+            DisableAllRules();
+            ToggleRule(PrivateFieldNamingRule.Name, enabled: true);
+
+            Verify(text, expected, runFormatter: false);
+        }
+
+        [Fact]
+        public void FieldNameExcluded()
+        {
+            var text = @"
+class C {
+    int field;
+
+    void M() {
+        N(this.field);
+    }
+}";
+
+            var expected = @"// header
+
+internal class C
+{
+    private int field;
+
+    private void M()
+    {
+        N(field);
+    }
+}";
+
+            ToggleRule(PrivateFieldNamingRule.Name, enabled: false);
+            Verify(text, expected, runFormatter: false);
+        }
+
         [Fact]
         public void FieldAssignment()
         {