Fixed bug 1763 and added unit tests

src/generator/AutoRest.CSharp.Unit.Tests/Bug1763.cs

@@ -0,0 +1,73 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+// 
+
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+using System.Text.RegularExpressions;
+using Microsoft.CodeAnalysis;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace AutoRest.CSharp.Unit.Tests
+{
+    public class Bug1763 : BugTest
+    {
+        public Bug1763(ITestOutputHelper output) : base(output)
+        {
+        }
+
+        /// <summary>
+        ///     https://github.com/Azure/autorest/issues/1763
+        ///     Verifies autorest succesfully generates code for models with properties starting with '_'
+        /// </summary>
+        [Fact]
+        public async Task VerifyUnderscoredClassMembers()
+        {
+            using (var fileSystem = GenerateCodeForTestFromSpec())
+            {
+                var result = await Compile(fileSystem);
+
+                // Expected Files
+                Assert.True(fileSystem.FileExists(@"GeneratedCode\Models\Pet.cs"));
+
+                // filter the warnings
+                var warnings = result.Messages.Where(
+                    each => each.Severity == DiagnosticSeverity.Warning
+                            && !SuppressWarnings.Contains(each.Id)).ToArray();
+
+                // filter the errors
+                var errors = result.Messages.Where(each => each.Severity == DiagnosticSeverity.Error).ToArray();
+
+                Write(warnings, fileSystem);
+                Write(errors, fileSystem);
+
+                // Don't proceed unless we have zero warnings.
+                Assert.Empty(warnings);
+                // Don't proceed unless we have zero Errors.
+                Assert.Empty(errors);
+
+                // Should also succeed.
+                Assert.True(result.Succeeded);
+
+                // try to load the assembly
+                var asm = Assembly.Load(result.Output.GetBuffer());
+                Assert.NotNull(asm);
+                var petModel = asm.ExportedTypes.First(type => type.FullName == "Test.Models.Pet" );
+                var idMember = petModel.GetMembers().First(member => member.Name == "_id" );
+                Assert.NotNull(idMember);
+
+                // now read from the file to ensure we use this. to access the members
+                var codeText = fileSystem.ReadFileAsText(@"GeneratedCode\Models\Pet.cs");
+                // get hold of the ctor
+                var regex = new Regex(Regex.Escape("public Pet(int _id, string name = default(string))") + @"[^}]+");
+                var match = regex.Match(codeText);
+                Assert.NotNull(match);
+                // verify the ctor has proper assignments
+                Assert.True(match.Groups[0].Value.Contains("this._id = _id"));
+                Assert.True(match.Groups[0].Value.Contains("this.Name = name"));
+            }
+        }
+    }
+}

src/generator/AutoRest.CSharp.Unit.Tests/Resource/Bug1763/Bug1763.yaml

@@ -0,0 +1,31 @@
+---
+swagger: '2.0'
+info:
+  title: TestAPI
+  description: test api
+  version: 0.0.0
+paths:
+  "/SimpleAPI/Pets":
+    put:
+      operationId: test_PutPet
+      description: Put pet with name
+      parameters:
+      - in: body
+        name: pet
+        description: pet to put
+        required: true
+        schema:
+          "$ref": "#/definitions/Pet"
+      responses:
+        '200':
+          description: Pet added to system
+definitions:
+  Pet:
+    description: simple pet to add
+    required:
+    - _id
+    properties:
+      _id:
+        type: integer
+      name:
+        type: string

src/generator/AutoRest.CSharp/Templates/Rest/Common/ModelTemplate.cshtml

@@ -54,7 +54,7 @@ namespace @(Settings.Namespace).@(Settings.ModelsName)
                 && p.IsRequired
                 && ((CompositeType)p.ModelType).ContainsConstantProperties))
             {
-            @:@(property.Name) = new @(property.ModelTypeName)();
+            @:this.@(property.Name) = new @(property.ModelTypeName)();
             }
         }
 </text>
@@ -88,7 +88,7 @@ namespace @(Settings.Namespace).@(Settings.ModelsName)
                      && p.IsRequired
                      && ((CompositeType)p.ModelType).ContainsConstantProperties))
             {
-            @:@(property.Name) = new @(property.ModelTypeName)();
+            @:this.@(property.Name) = new @(property.ModelTypeName)();
             }
 
             foreach (var property in Model.Properties.Where(p => !p.IsConstant))
@@ -100,7 +100,7 @@ namespace @(Settings.Namespace).@(Settings.ModelsName)
                 }
                 else
                 {
-            @:@(property.Name) = @propName;
+            @:this.@(property.Name) = @propName;
                 }
             }            
 
@@ -208,7 +208,7 @@ namespace @(Settings.Namespace).@(Settings.ModelsName)
             foreach (PropertyCs property in Model.Properties.Where(p => p.IsRequired && !p.IsReadOnly && !p.IsConstant && p.IsNullable() ))
             {
                 anythingToValidate = true;
-            @:if (@property.Name == null)
+            @:if (this.@property.Name == null)
             @:{
                 @:throw new Microsoft.Rest.ValidationException(Microsoft.Rest.ValidationRules.CannotBeNull, "@property.Name");
             @:}