Add plumbing for imports and includes

Groundwork for support of _ViewImports _ViewStart and others.

src/Microsoft.AspNetCore.Razor.Evolution/DefaultRazorCodeDocument.cs

@@ -2,12 +2,17 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
+using System.Linq;
 
 namespace Microsoft.AspNetCore.Razor.Evolution
 {
     internal class DefaultRazorCodeDocument : RazorCodeDocument
     {
-        public DefaultRazorCodeDocument(RazorSourceDocument source)
+        public DefaultRazorCodeDocument(
+            RazorSourceDocument source,
+            IEnumerable<RazorSourceDocument> imports,
+            IEnumerable<RazorSourceDocument> includes)
         {
             if (source == null)
             {
@@ -15,10 +20,16 @@ namespace Microsoft.AspNetCore.Razor.Evolution
             }
 
             Source = source;
+            Imports = imports?.ToArray() ?? RazorSourceDocument.EmptyArray;
+            Includes = includes?.ToArray() ?? RazorSourceDocument.EmptyArray;
 
             Items = new DefaultItemCollection();
         }
 
+        public override IReadOnlyList<RazorSourceDocument> Imports { get; }
+
+        public override IReadOnlyList<RazorSourceDocument> Includes { get; }
+
         public override ItemCollection Items { get; }
 
         public override RazorSourceDocument Source { get; }

src/Microsoft.AspNetCore.Razor.Evolution/RazorCodeDocument.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Evolution
 {
@@ -14,11 +15,28 @@ namespace Microsoft.AspNetCore.Razor.Evolution
                 throw new ArgumentNullException(nameof(source));
             }
 
-            return new DefaultRazorCodeDocument(source);
+            return Create(source, imports: null, includes: null);
         }
 
+        public static RazorCodeDocument Create(
+            RazorSourceDocument source,
+            IEnumerable<RazorSourceDocument> imports,
+            IEnumerable<RazorSourceDocument> includes)
+        {
+            if (source == null)
+            {
+                throw new ArgumentNullException(nameof(source));
+            }
+            
+            return new DefaultRazorCodeDocument(source, imports, includes);
+        }
+
+        public abstract IReadOnlyList<RazorSourceDocument> Imports { get; }
+
         public abstract ItemCollection Items { get; }
 
+        public abstract IReadOnlyList<RazorSourceDocument> Includes { get; }
+
         public abstract RazorSourceDocument Source { get; }
     }
 }

src/Microsoft.AspNetCore.Razor.Evolution/RazorSourceDocument.cs

@@ -9,6 +9,8 @@ namespace Microsoft.AspNetCore.Razor.Evolution
 {
     public abstract class RazorSourceDocument
     {
+        internal static readonly RazorSourceDocument[] EmptyArray = new RazorSourceDocument[0];
+
         public abstract Encoding Encoding { get; }
 
         public abstract string Filename { get; }

test/Microsoft.AspNetCore.Razor.Evolution.Test/DefaultRazorCodeDocumentTest.cs

@@ -13,12 +13,44 @@ namespace Microsoft.AspNetCore.Razor.Evolution
             // Arrange
             var source = TestRazorSourceDocument.Create();
 
+            var imports = new RazorSourceDocument[]
+            {
+                TestRazorSourceDocument.Create(),
+            };
+
+            var includes = new RazorSourceDocument[]
+            {
+                TestRazorSourceDocument.Create(),
+            };
+
             // Act
-            var code = new DefaultRazorCodeDocument(source);
+            var code = new DefaultRazorCodeDocument(source, imports, includes);
 
             // Assert
             Assert.Same(source, code.Source);
             Assert.NotNull(code.Items);
+
+            Assert.NotSame(imports, code.Imports);
+            Assert.Collection(imports, d => Assert.Same(imports[0], d));
+
+            Assert.NotSame(includes, code.Includes);
+            Assert.Collection(includes, d => Assert.Same(includes[0], d));
+        }
+
+        [Fact]
+        public void Ctor_AllowsNullForImportsAndIncludes()
+        {
+            // Arrange
+            var source = TestRazorSourceDocument.Create();
+
+            // Act
+            var code = new DefaultRazorCodeDocument(source, imports: null, includes: null);
+
+            // Assert
+            Assert.Same(source, code.Source);
+            Assert.NotNull(code.Items);
+            Assert.Empty(code.Imports);
+            Assert.Empty(code.Includes);
         }
     }
 }

test/Microsoft.AspNetCore.Razor.Evolution.Test/RazorCodeDocumentTest.cs

@@ -20,5 +20,51 @@ namespace Microsoft.AspNetCore.Razor.Evolution
             Assert.Same(source, code.Source);
             Assert.NotNull(code.Items);
         }
+
+        [Fact]
+        public void Create_WithImportsAndIncludes()
+        {
+            // Arrange
+            var source = TestRazorSourceDocument.Create();
+
+            var imports = new RazorSourceDocument[]
+            {
+                TestRazorSourceDocument.Create(),
+            };
+
+            var includes = new RazorSourceDocument[]
+            {
+                TestRazorSourceDocument.Create(),
+            };
+
+            // Act
+            var code = RazorCodeDocument.Create(source, imports, includes);
+
+            // Assert
+            Assert.Same(source, code.Source);
+            Assert.NotNull(code.Items);
+
+            Assert.NotSame(imports, code.Imports);
+            Assert.Collection(imports, d => Assert.Same(imports[0], d));
+
+            Assert.NotSame(includes, code.Includes);
+            Assert.Collection(includes, d => Assert.Same(includes[0], d));
+        }
+
+        [Fact]
+        public void Create_WithImportsAndIncludes_AllsNull()
+        {
+            // Arrange
+            var source = TestRazorSourceDocument.Create();
+
+            // Act
+            var code = RazorCodeDocument.Create(source, imports: null, includes: null);
+
+            // Assert
+            Assert.Same(source, code.Source);
+            Assert.NotNull(code.Items);
+            Assert.Empty(code.Imports);
+            Assert.Empty(code.Includes);
+        }
     }
 }

test/Microsoft.AspNetCore.Razor.Evolution.Test/TestRazorCodeDocument.cs

@@ -1,6 +1,8 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections.Generic;
+
 namespace Microsoft.AspNetCore.Razor.Evolution
 {
     internal class TestRazorCodeDocument : DefaultRazorCodeDocument
@@ -8,17 +10,20 @@ namespace Microsoft.AspNetCore.Razor.Evolution
         public static TestRazorCodeDocument CreateEmpty()
         {
             var source = TestRazorSourceDocument.Create(content: string.Empty);
-            return new TestRazorCodeDocument(source);
+            return new TestRazorCodeDocument(source, imports: null, includes: null);
         }
 
         public static TestRazorCodeDocument Create(string content)
         {
             var source = TestRazorSourceDocument.Create(content);
-            return new TestRazorCodeDocument(source);
+            return new TestRazorCodeDocument(source, imports: null, includes: null);
         }
 
-        private TestRazorCodeDocument(RazorSourceDocument source)
-            : base(source)
+        private TestRazorCodeDocument(
+            RazorSourceDocument source,
+            IEnumerable<RazorSourceDocument> imports,
+            IEnumerable<RazorSourceDocument> includes)
+            : base(source, imports, includes)
         {
         }
     }