add test case: build only

Signed-off-by: GitHub <[email protected]>

Author: satotake

local/e2e/compose/fixtures/dry-run-test/pull/compose.yaml

@@ -8,4 +8,7 @@ services:
   expectedFail:
     # this image is not expected to be registered on any registries
     image: expected-not-to-be-registered
+    command: top
+  expectedSkip-build:
+    build: Dockerfile
     command: top

pkg/compose/pull.go

@@ -191,7 +191,10 @@ func getPullPlan(service types.ServiceConfig, localDigests []string, dstrDigest
 		}
 	}
 
-	if dstrDigest == "" {
+	if service.Image == "" {
+		// build only service
+		plan = pullPlanSkip
+	} else if dstrDigest == "" {
 		plan = pullPlanFail
 	} else if canSkip {
 		plan = pullPlanSkip