cipd: Client can resolve tags to instance IDs.

go/src/infra/tools/cipd/common/common_test.go

Index: go/src/infra/tools/cipd/common/common_test.go
diff --git a/go/src/infra/tools/cipd/common/common_test.go b/go/src/infra/tools/cipd/common/common_test.go
index 2f917a1e14e2bbcd992aa29b9a4263db222fa1ab..1690900dba716523e9cf99300d1990d34c6c2b18 100644
--- a/go/src/infra/tools/cipd/common/common_test.go
+++ b/go/src/infra/tools/cipd/common/common_test.go
@@ -55,13 +55,21 @@ func TestValidateInstanceTag(t *testing.T) {
 }
 
 func TestValidatePin(t *testing.T) {
-	Convey("TestValidatePin works", t, func() {
+	Convey("ValidatePin works", t, func() {
 		So(ValidatePin(Pin{"good/name", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"}), ShouldBeNil)
 		So(ValidatePin(Pin{"BAD/name", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"}), ShouldNotBeNil)
 		So(ValidatePin(Pin{"good/name", "aaaaaaaaaaa"}), ShouldNotBeNil)
 	})
 }
 
+func TestValidateInstanceVersion(t *testing.T) {
+	Convey("ValidateInstanceVersion works", t, func() {
+		So(ValidateInstanceVersion("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"), ShouldBeNil)
+		So(ValidateInstanceVersion("good:tag"), ShouldBeNil)
+		So(ValidateInstanceVersion("BADTAG:"), ShouldNotBeNil)
+	})
+}
+
 func TestPinToString(t *testing.T) {
 	Convey("Pin.String works", t, func() {
 		So(