Allow opting out of transitive private assets package reference packing

Sometimes it may be useful to just pack the top-level dependency from a reference (i.e. you're getting the other deps by some other means, or the environment they run on doesn't require them, such as for Microsoft.Build.Framework, say).

This allows just setting PackTransitive=false to stop the transitivity.

Fixes #37

README.md

@@ -172,9 +172,9 @@ Package references are turned into package dependencies by default (essentially
 
 Build-only dependencies that don't contribute assemblies to the output (i.e. analyzers or things like [GitInfo](https://github.com/kzu/GitInfo) or [ThisAssembly](https://github.com/kzu/ThisAssembly) won't cause any extra items).
 
-This even works transitively, so if you use *PrivateAssets=all* on package reference *A*, which in turn has a package dependency on *B* and *B* in turn depends on *C*, all of *A*, *B* and *C* assets will be packed. 
+This even works transitively, so if you use *PrivateAssets=all* on package reference *A*, which in turn has a package dependency on *B* and *B* in turn depends on *C*, all of *A*, *B* and *C* assets will be packed. You can opt out of the transitive packing with `PackTransitive=false`.
 
-As usual, you can change this default behavior by using `Pack=false` metadata.
+As usual, you can change this default behavior by using `Pack=false` metadata. 
 
 ### ProjectReference
 

src/NuGetizer.Tasks/NuGetizer.Inference.targets

@@ -307,11 +307,11 @@ Copyright (c) .NET Foundation. All rights reserved.
                                             '%(Facade)' != 'true' and 
                                             '%(FrameworkFile)' != 'true' and 
                                             '%(Pack)' != 'false'"/>
-      <_PrivateAssetsPackageReference Include="@(PackageReference -> WithMetadataValue('PrivateAssets', 'all'))"
-                                      Condition="'%(PackageReference.IsImplicitlyDefined)' != 'true' and '%(PackageReference.Pack)' != 'false'"/>
+      <_TransitivePackageReference Include="@(PackageReference -> WithMetadataValue('PrivateAssets', 'all'))"
+                                   Condition="'%(PackageReference.IsImplicitlyDefined)' != 'true' and '%(PackageReference.Pack)' != 'false' and '%(PackageReference.PackTransitive)' != 'false'"/>
     </ItemGroup>
-    <InferImplicitPackageReference Condition="'@(_PrivateAssetsPackageReference)' != '' and '@(PackageDependencies)' != ''"
-                                   PackageReferences="@(_PrivateAssetsPackageReference)"
+    <InferImplicitPackageReference Condition="'@(_TransitivePackageReference)' != '' and '@(PackageDependencies)' != ''"
+                                   PackageReferences="@(_TransitivePackageReference)"
                                    PackageDependencies="@(PackageDependencies)">
       <Output TaskParameter="ImplicitPackageReferences" ItemName="ImplicitPackageReference" />
     </InferImplicitPackageReference>

src/NuGetizer.Tests/InlineProjectTests.cs

@@ -468,7 +468,7 @@ public void when_pack_on_build_multitargeting_then_contains_all_targets()
         }
 
         [Fact]
-        public void when_packing_transive_reference_then_packs_lib()
+        public void when_packing_private_transive_reference_then_packs_lib()
         {
             var result = Builder.BuildProject(@"
 <Project Sdk='Microsoft.NET.Sdk'>
@@ -495,5 +495,35 @@ public void when_packing_transive_reference_then_packs_lib()
             Assert.Contains(result.Items, item 
                 => item.GetMetadata("FullPath").EndsWith(Path.Combine("lib", "netstandard2.0", "System.Threading.Tasks.Extensions.dll")));
         }
+
+        [Fact]
+        public void when_packing_private_dependency_then_can_opt_out_of_transitive()
+        {
+            var result = Builder.BuildProject(@"
+<Project Sdk='Microsoft.NET.Sdk'>
+  <PropertyGroup>
+    <IsPackable>true</IsPackable>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include='Scriban' Version='3.0.4' PrivateAssets='all' PackTransitive='false' />
+  </ItemGroup>
+</Project>", output: output);
+
+            result.AssertSuccess(output);
+
+            Assert.DoesNotContain(result.Items, item => item.Matches(new
+            {
+                Filename = "System.Runtime.CompilerServices.Unsafe",
+                Extension = ".dll"
+            }));
+
+            Assert.DoesNotContain(result.Items, item => item.Matches(new
+            {
+                Filename = "System.Threading.Tasks.Extensions",
+                Extension = ".dll"
+            }));
+        }
+
     }
 }