Fix CargoComponent.PackageURL

Author: RodneyRichardson

src/Microsoft.ComponentDetection.Contracts/TypedComponent/CargoComponent.cs

@@ -36,7 +36,7 @@ public CargoComponent(string name, string version, string author = null, string
 
     public override ComponentType Type => ComponentType.Cargo;
 
-    public override PackageURL PackageUrl => new PackageURL("cargo", string.Empty, this.Name, this.Version, null, string.Empty);
+    public override PackageURL PackageUrl => new PackageURL("cargo", null, this.Name, this.Version, null, null);
 
     protected override string ComputeId() => $"{this.Name} {this.Version} - {this.Type}";
 }

test/Microsoft.ComponentDetection.Contracts.Tests/PurlGenerationTests.cs

@@ -109,4 +109,16 @@ public void CocoaPodNameShouldPurlWithCustomQualifier()
 
         packageOne.PackageUrl.ToString().Should().Be("pkg:cocoapods/[email protected]?repository_url=https://custom_repo.example.com/path/to/repo/specs.git");
     }
+
+    [TestMethod]
+    public void CargoShouldSupportPurl()
+    {
+        // https://github.com/package-url/purl-spec/blob/main/PURL-TYPES.rst#cargo
+        var packageOne = new CargoComponent("rand", "0.7.2");
+        var packageTwo = new CargoComponent("rand", "0.7.3", "RodneyRichardson", "MIT", "https://custom_repo.example.com/path/to/repo/specs.git");
+
+        packageOne.PackageUrl.Type.Should().Be("cargo");
+        packageOne.PackageUrl.ToString().Should().Be("pkg:cargo/[email protected]");
+        packageTwo.PackageUrl.ToString().Should().Be("pkg:cargo/[email protected]");
+    }
 }