tests: fix bug due to random numbers being used

When using hard coded subnet values in tests,
it's important that they don't accidently end
up being the same as acquired leases.
Use SubnetMin/SubnetMax in config to segrate
hard coded and dynamically allocatable ranges.

Fixes #381

subnet/subnet_test.go

@@ -35,10 +35,14 @@ func newDummyRegistry() *MockSubnetRegistry {
 	exp := time.Time{}
 
 	subnets := []Lease{
+		// leases within SubnetMin-SubnetMax range
 		{ip.IP4Net{ip.MustParseIP4("10.3.1.0"), 24}, attrs, exp, 10},
 		{ip.IP4Net{ip.MustParseIP4("10.3.2.0"), 24}, attrs, exp, 11},
 		{ip.IP4Net{ip.MustParseIP4("10.3.4.0"), 24}, attrs, exp, 12},
 		{ip.IP4Net{ip.MustParseIP4("10.3.5.0"), 24}, attrs, exp, 13},
+
+		// hand created lease outside the range of subnetMin-SubnetMax for testing removal
+		{ip.IP4Net{ip.MustParseIP4("10.3.31.0"), 24}, attrs, exp, 13},
 	}
 
 	config := `{ "Network": "10.3.0.0/16", "SubnetMin": "10.3.1.0", "SubnetMax": "10.3.25.0" }`
@@ -151,13 +155,22 @@ func TestWatchLeaseAdded(t *testing.T) {
 	}
 
 	expected := ip.IP4Net{
-		IP:        ip.MustParseIP4("10.3.6.0"),
+		IP:        ip.MustParseIP4("10.3.30.0"),
 		PrefixLen: 24,
 	}
+	// Sanity check to make sure acquired lease is not this.
+	// It shouldn't be as SubnetMin/SubnetMax in config is [10.3.1.0/24 to 10.3.25.0/24]
+	if l.Subnet.Equal(expected) {
+		t.Fatalf("Acquired lease conflicts with one about to create")
+	}
+
 	attrs := &LeaseAttrs{
 		PublicIP: ip.MustParseIP4("1.1.1.1"),
 	}
-	msr.createSubnet(ctx, "_", expected, attrs, 0)
+	_, err := msr.createSubnet(ctx, "_", expected, attrs, 0)
+	if err != nil {
+		t.Fatalf("createSubnet filed: %v", err)
+	}
 
 	evtBatch = <-events
 
@@ -196,7 +209,13 @@ func TestWatchLeaseRemoved(t *testing.T) {
 		}
 	}
 
-	expected := ip.IP4Net{ip.MustParseIP4("10.3.4.0"), 24}
+	expected := ip.IP4Net{ip.MustParseIP4("10.3.31.0"), 24}
+	// Sanity check to make sure acquired lease is not this.
+	// It shouldn't be as SubnetMin/SubnetMax in config is [10.3.1.0/24 to 10.3.25.0/24]
+	if l.Subnet.Equal(expected) {
+		t.Fatalf("Acquired lease conflicts with one about to create")
+	}
+
 	msr.expireSubnet("_", expected)
 
 	evtBatch = <-events