[vpython] Add conditional packages based on PEP425

vpython/spec/spec_test.go

Index: vpython/spec/spec_test.go
diff --git a/vpython/spec/spec_test.go b/vpython/spec/spec_test.go
index abc17c29f85af1fac6ead54ac2469b228d1f2e66..e7fe295e0203212255e1164816630cd4434165ce 100644
--- a/vpython/spec/spec_test.go
+++ b/vpython/spec/spec_test.go
@@ -16,19 +16,28 @@ import (
 func TestNormalizeAndHash(t *testing.T) {
 	t.Parallel()
 
-	pkgFoo := &vpython.Spec_Package{Name: "foo", Version: "1"}
-	pkgBar := &vpython.Spec_Package{Name: "bar", Version: "2"}
-	pkgBaz := &vpython.Spec_Package{Name: "baz", Version: "3"}
-
 	Convey(`Test manifest generation`, t, func() {
-		var env vpython.Environment
+		otherTag := &vpython.Pep425Tag{Version: "otherVersion", Abi: "otherABI", Arch: "otherArch"}
+		maybeTag := &vpython.Pep425Tag{Version: "maybeVersion", Abi: "maybeABI", Arch: "maybeArch"}
+
+		pkgFoo := &vpython.Spec_Package{Name: "foo", Version: "1"}
+		pkgBar := &vpython.Spec_Package{Name: "bar", Version: "2"}
+		pkgBaz := &vpython.Spec_Package{Name: "baz", Version: "3"}
+		pkgMaybe := &vpython.Spec_Package{Name: "maybe", Version: "3", MatchTag: []*vpython.Pep425Tag{
+			{Version: maybeTag.Version},
+		}}
+
+		env := vpython.Environment{
+			Pep425Tag: []*vpython.Pep425Tag{otherTag},
+		}
 		var rt vpython.Runtime
 
 		Convey(`Will normalize an empty spec`, func() {
 			So(NormalizeEnvironment(&env), ShouldBeNil)
 			So(env, ShouldResemble, vpython.Environment{
-				Spec:    &vpython.Spec{},
-				Runtime: &vpython.Runtime{},
+				Spec:      &vpython.Spec{},
+				Runtime:   &vpython.Runtime{},
+				Pep425Tag: []*vpython.Pep425Tag{otherTag},
 			})
 		})
 
@@ -46,6 +55,28 @@ func TestNormalizeAndHash(t *testing.T) {
 				So(Hash(env.Spec, &rt, "extra"), ShouldEqual, "140a02bb88b011d4aceafb9533266288fd4b441c3bdb70494419b3ef76457f34")
 			})
 
+			Convey(`With match tags`, func() {
+				env.Spec.Wheel = []*vpython.Spec_Package{pkgFoo, pkgMaybe}
+
+				Convey(`Will omit the package if it doesn't match a tag`, func() {
+					So(NormalizeEnvironment(&env), ShouldBeNil)
+					So(env.Spec, ShouldResemble, &vpython.Spec{
+						Wheel: []*vpython.Spec_Package{pkgFoo},
+					})
+				})
+
+				Convey(`Will include the package if it matches a tag, and strip the match field.`, func() {
+					env.Pep425Tag = append(env.Pep425Tag, maybeTag)
+
+					So(NormalizeEnvironment(&env), ShouldBeNil)
+
+					pkgMaybe.MatchTag = nil
+					So(env.Spec, ShouldResemble, &vpython.Spec{
+						Wheel: []*vpython.Spec_Package{pkgFoo, pkgMaybe},
+					})
+				})
+			})
+
 			Convey(`Will fail to normalize if there are duplicate wheels.`, func() {
 				env.Spec.Wheel = []*vpython.Spec_Package{pkgFoo, pkgFoo, pkgBar, pkgBaz}
 				So(NormalizeEnvironment(&env), ShouldErrLike, "duplicate spec entries")