Added test for global security reference

Author: darrelmiller

src/Microsoft.OpenApi/Services/OpenApiWalker.cs

@@ -44,6 +44,7 @@ public void Walk(OpenApiDocument doc)
             Walk(OpenApiConstants.Servers, () => Walk(doc.Servers));
             Walk(OpenApiConstants.Paths, () => Walk(doc.Paths));
             Walk(OpenApiConstants.Components, () => Walk(doc.Components));
+            Walk(OpenApiConstants.Security, () => Walk(doc.SecurityRequirements));
             Walk(OpenApiConstants.ExternalDocs, () => Walk(doc.ExternalDocs));
             Walk(OpenApiConstants.Tags, () => Walk(doc.Tags));
             Walk(doc as IOpenApiExtensible);

test/Microsoft.OpenApi.Readers.Tests/Microsoft.OpenApi.Readers.Tests.csproj

@@ -13,6 +13,7 @@
         <AssemblyOriginatorKeyFile>..\..\src\Microsoft.OpenApi.snk</AssemblyOriginatorKeyFile>
     </PropertyGroup>
     <ItemGroup>
+      <None Remove="V3Tests\Samples\OpenApiDocument\securedApi.yaml" />
       <None Remove="V3Tests\Samples\OpenApiOperation\securedOperation.yaml" />
     </ItemGroup>
     <ItemGroup>
@@ -97,6 +98,7 @@
       <EmbeddedResource Include="V3Tests\Samples\OpenApiDocument\petStoreWithTagAndSecurity.yaml">
         <CopyToOutputDirectory>Never</CopyToOutputDirectory>
       </EmbeddedResource>
+      <EmbeddedResource Include="V3Tests\Samples\OpenApiDocument\securedApi.yaml" />
       <EmbeddedResource Include="V3Tests\Samples\OpenApiEncoding\advancedEncoding.yaml">
         <CopyToOutputDirectory>Never</CopyToOutputDirectory>
       </EmbeddedResource>

test/Microsoft.OpenApi.Readers.Tests/V3Tests/OpenApiDocumentTests.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using FluentAssertions;
 using Microsoft.OpenApi.Models;
 using Newtonsoft.Json;
@@ -1110,5 +1111,18 @@ public void ParsePetStoreExpandedShouldSucceed()
             context.ShouldBeEquivalentTo(
                     new OpenApiDiagnostic() { SpecificationVersion = OpenApiSpecVersion.OpenApi3_0 });
         }
+
+        [Fact]
+        public void GlobalSecurityRequirementShouldReferenceSecurityScheme()
+        {
+            using (var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "securedApi.yaml")))
+            {
+                var openApiDoc = new OpenApiStreamReader().Read(stream, out var diagnostic);
+
+                var securityRequirement = openApiDoc.SecurityRequirements.First();
+
+                Assert.Same(securityRequirement.Keys.First(), openApiDoc.Components.SecuritySchemes.First().Value);
+            }
+        }
     }
 }

test/Microsoft.OpenApi.Readers.Tests/V3Tests/OpenApiOperationTests.cs

@@ -23,5 +23,7 @@ public void OperationWithSecurityRequirementShouldReferenceSecurityScheme()
                 Assert.Same(securityRequirement.Keys.First(), openApiDoc.Components.SecuritySchemes.First().Value);
             }
         }
+
+     
     }
 }

test/Microsoft.OpenApi.Readers.Tests/V3Tests/Samples/OpenApiDocument/securedApi.yaml

@@ -0,0 +1,12 @@
+openapi: 3.0.0
+info:
+  title: Example of Security Requirement referencing a security scheme
+  version: 1.0.0
+paths: {}
+security:
+  - basicAuth: []
+components:
+  securitySchemes:
+    basicAuth:
+      type: http
+      scheme: basic