functional: make TestUnitSubmit() use a helper util.WaitForState

TestUnitSubmit() now makes use of a new helper runListUnits() that
depends on util.WaitForState(), instead of running list-units every
time. This change will also help the whole functional test become
less racy.

functional/unit_action_test.go

@@ -57,6 +57,9 @@ func TestUnitRunnable(t *testing.T) {
 	}
 }
 
+// TestUnitSubmit checks if a unit becomes submitted and destroyed successfully.
+// First it submits a unit, and destroys the unit, verifies it's destroyed,
+// finally submits the unit again.
 func TestUnitSubmit(t *testing.T) {
 	cluster, err := platform.NewNspawnCluster("smoke")
 	if err != nil {
@@ -73,48 +76,47 @@ func TestUnitSubmit(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	unitFile := "fixtures/units/hello.service"
+
 	// submit a unit and assert it shows up
-	if _, _, err := cluster.Fleetctl(m, "submit", "fixtures/units/hello.service"); err != nil {
+	_, _, err = cluster.Fleetctl(m, "submit", unitFile)
+	if err != nil {
 		t.Fatalf("Unable to submit fleet unit: %v", err)
 	}
-	stdout, _, err := cluster.Fleetctl(m, "list-units", "--no-legend")
+
+	// wait until the unit gets submitted up to 15 seconds
+	err = runListUnits(cluster, m, 1)
 	if err != nil {
 		t.Fatalf("Failed to run list-units: %v", err)
 	}
-	units := strings.Split(strings.TrimSpace(stdout), "\n")
-	if len(units) != 1 {
-		t.Fatalf("Did not find 1 unit in cluster: \n%s", stdout)
-	}
 
 	// submitting the same unit should not fail
-	if _, _, err = cluster.Fleetctl(m, "submit", "fixtures/units/hello.service"); err != nil {
+	_, _, err = cluster.Fleetctl(m, "submit", unitFile)
+	if err != nil {
 		t.Fatalf("Expected no failure when double-submitting unit, got this: %v", err)
 	}
 
 	// destroy the unit and ensure it disappears from the unit list
-	if _, _, err := cluster.Fleetctl(m, "destroy", "fixtures/units/hello.service"); err != nil {
+	_, _, err = cluster.Fleetctl(m, "destroy", unitFile)
+	if err != nil {
 		t.Fatalf("Failed to destroy unit: %v", err)
 	}
-	stdout, _, err = cluster.Fleetctl(m, "list-units", "--no-legend")
+	// wait until the unit gets submitted up to 15 seconds
+	err = runListUnits(cluster, m, 0)
 	if err != nil {
 		t.Fatalf("Failed to run list-units: %v", err)
 	}
-	if strings.TrimSpace(stdout) != "" {
-		t.Fatalf("Did not find 0 units in cluster: \n%s", stdout)
-	}
 
 	// submitting the unit after destruction should succeed
-	if _, _, err := cluster.Fleetctl(m, "submit", "fixtures/units/hello.service"); err != nil {
+	_, _, err = cluster.Fleetctl(m, "submit", unitFile)
+	if err != nil {
 		t.Fatalf("Unable to submit fleet unit: %v", err)
 	}
-	stdout, _, err = cluster.Fleetctl(m, "list-units", "--no-legend")
+	// wait until the unit gets submitted up to 15 seconds
+	err = runListUnits(cluster, m, 1)
 	if err != nil {
 		t.Fatalf("Failed to run list-units: %v", err)
 	}
-	units = strings.Split(strings.TrimSpace(stdout), "\n")
-	if len(units) != 1 {
-		t.Fatalf("Did not find 1 unit in cluster: \n%s", stdout)
-	}
 }
 
 func TestUnitRestart(t *testing.T) {