Ensure version/revision are set during testing

Add link flags to our test target to ensure that the
version and revision are set during unit tests.

Signed-off-by: Yasin Turan <turyasin@amazon.com>

Author: turan18

Makefile

@@ -85,7 +85,7 @@ vendor:
 
 test:
 	@echo "$@"
-	@GO111MODULE=$(GO111MODULE_VALUE) go test $(GO_TEST_FLAGS) -race ./...
+	@GO111MODULE=$(GO111MODULE_VALUE) go test $(GO_TEST_FLAGS) $(GO_LD_FLAGS) -race ./...
 
 integration: build
 	@echo "$@"

version/version.go

@@ -32,10 +32,12 @@
 
 package version
 
+const Unset = "<unknown>"
+
 var (
 	// Version is the version number. Filled in at linking time (via Makefile).
-	Version = "<unknown>"
+	Version = Unset
 
 	// Revision is the VCS (e.g. git) revision. Filled in at linking time (via Makefile).
-	Revision = "<unknown>"
+	Revision = Unset
 )

version/version_test.go

@@ -0,0 +1,41 @@
+/*
+   Copyright The Soci Snapshotter Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package version
+
+import "testing"
+
+func TestVersion(t *testing.T) {
+	if Version == Unset {
+		t.Fatalf("version is unset")
+	}
+}