From 8eb28f57bf359044b56e7fef4a6a7e0a26cd735b Mon Sep 17 00:00:00 2001
From: Marten Smits <m.smits@furore.com>
Date: Mon, 30 May 2022 13:35:40 +0200
Subject: [PATCH] added factory method for creating an FHIR Core Package
 resolver

---
 .../Source/FhirPackageSourceTests.cs             | 16 ++++++++++++++++
 .../Specification/Source/FhirPackageSource.cs    | 13 +++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/Hl7.Fhir.Specification.Tests/Source/FhirPackageSourceTests.cs b/src/Hl7.Fhir.Specification.Tests/Source/FhirPackageSourceTests.cs
index d169ca81fe..bd50e97a9d 100644
--- a/src/Hl7.Fhir.Specification.Tests/Source/FhirPackageSourceTests.cs
+++ b/src/Hl7.Fhir.Specification.Tests/Source/FhirPackageSourceTests.cs
@@ -28,6 +28,22 @@ public async System.Threading.Tasks.Task TestResolveByCanonicalUri()
             adm_gender.Expansion.Contains.Should().Contain(c => c.System == "http://hl7.org/fhir/administrative-gender" && c.Code == "other");
         }
 
+        [TestMethod, TestCategory("IntegrationTest")]
+        public async System.Threading.Tasks.Task TestCorePackageSource()
+        {
+            var corePackageSource = FhirPackageSource.CreateFhirCorePackageSource();
+
+            //check StructureDefinitions
+            var pat = await corePackageSource.ResolveByCanonicalUriAsync("http://hl7.org/fhir/StructureDefinition/Patient").ConfigureAwait(false) as StructureDefinition;
+            pat.Should().NotBeNull();
+            pat.Url.Should().Be("http://hl7.org/fhir/StructureDefinition/Patient");
+
+            //check expansions
+            var adm_gender = await corePackageSource.ResolveByCanonicalUriAsync("http://hl7.org/fhir/ValueSet/administrative-gender").ConfigureAwait(false) as ValueSet;
+            adm_gender.Should().NotBeNull();
+            adm_gender.Expansion.Contains.Should().Contain(c => c.System == "http://hl7.org/fhir/administrative-gender" && c.Code == "other");
+        }
+
         [TestMethod]
         public void TestListFileNames()
         {
diff --git a/src/Hl7.Fhir.Specification/Specification/Source/FhirPackageSource.cs b/src/Hl7.Fhir.Specification/Specification/Source/FhirPackageSource.cs
index df0734df0d..aad53e428b 100644
--- a/src/Hl7.Fhir.Specification/Specification/Source/FhirPackageSource.cs
+++ b/src/Hl7.Fhir.Specification/Specification/Source/FhirPackageSource.cs
@@ -21,6 +21,10 @@ public static class CorePackageFileNames
     /// <summary>Reads FHIR version specific artifacts (Profiles, ValueSets, ...) from the FHIR Packages</summary>
     public class FhirPackageSource : IAsyncResourceResolver, IArtifactSource, IConformanceSource
     {
+        private const string FHIR_CORE_PACKAGE_NAME = "hl7.fhir.r5.core";
+        private const string FHIR_CORE_EXPANSIONS_PACKAGE_NAME = "hl7.fhir.r5.expansions";
+        private const string FHIR_PACKAGE_SERVER = "http://packages2.fhir.org/packages";
+
         private CommonFhirPackageSource _resolver;
 
         /// <summary>Create a new <see cref="FhirPackageSource"/> instance to read FHIR artifacts from the referenced FHIR packages.</summary>
@@ -40,6 +44,15 @@ public FhirPackageSource(string packageServer, string[] packageNames)
             _resolver = new CommonFhirPackageSource(inspector, packageServer, packageNames);
         }
 
+        /// <summary>
+        /// Create a new <see cref="FhirPackageSource"/> that includes the all Core FHIR artifacts including the expanded value sets.
+        /// </summary>
+        /// <remarks>Needs an active internet connection for first installation, FHIR packages will be cached locally after</remarks>
+        /// <returns>A new <see cref="FhirPackageSource"/> that includes all Core FHIR definitions/artifacts including the expanded value sets.</returns>
+        public static FhirPackageSource CreateFhirCorePackageSource()
+        {
+            return new FhirPackageSource(FHIR_PACKAGE_SERVER, new string[] { FHIR_CORE_PACKAGE_NAME, FHIR_CORE_EXPANSIONS_PACKAGE_NAME });
+        }
 
         ///<inheritdoc/>
         public async Task<Resource?> ResolveByCanonicalUriAsync(string uri)