test(interfaces): Add tests for network conversion

These tests should be an exhaustive set of tests for the parsing
of Debian interface files and generation of equivilent networkd
config files.

network/network_test.go

@@ -0,0 +1,42 @@
+package network
+
+import (
+	"testing"
+)
+
+func TestFormatConfigs(t *testing.T) {
+	for in, n := range map[string]int{
+		"":                                                    0,
+		"line1\\\nis long":                                    1,
+		"#comment":                                            0,
+		"#comment\\\ncomment":                                 0,
+		"  #comment \\\n comment\nline 1\nline 2\\\n is long": 2,
+	} {
+		lines := formatConfig(in)
+		if len(lines) != n {
+			t.Fatalf("bad number of lines for config %q: got %d, want %d", in, len(lines), n)
+		}
+	}
+}
+
+func TestProcessDebianNetconf(t *testing.T) {
+	for _, tt := range []struct {
+		in   string
+		fail bool
+		n    int
+	}{
+		{"", false, 0},
+		{"iface", true, -1},
+		{"auto eth1\nauto eth2", false, 0},
+		{"iface eth1 inet manual", false, 1},
+	} {
+		interfaces, err := ProcessDebianNetconf(tt.in)
+		failed := err != nil
+		if tt.fail != failed {
+			t.Fatalf("bad failure state for %q: got %b, want %b", failed, tt.fail)
+		}
+		if tt.n != -1 && tt.n != len(interfaces) {
+			t.Fatalf("bad number of interfaces for %q: got %d, want %q", tt.in, len(interfaces), tt.n)
+		}
+	}
+}