Test the refusal of a jail whose pattern names the host twice

Main refuses such a jail (fail2ban would refuse its whole configuration and
keep no bans), but no test held it: the only one sat untracked in an old
worktree. Issue 959.

internal/catalogue/jail_problems_test.go

@@ -0,0 +1,49 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// A jail whose pattern names <HOST> twice is refused by name: fail2ban would read it as a duplicate
+// capture group and refuse its whole configuration, leaving the machine with no bans at all — which
+// is what happened on the control node the day this was built (novox/hq ADR 0179).
+func TestAJailsPatternNamesTheHostOncePerShape(t *testing.T) {
+	twice := Manifest{Module: "route-proxy", Jails: []Jail{{
+		Name:      "route-proxy",
+		Failregex: `^.*(?:refused for <HOST>:\d+|asked from <HOST>:\d+)$`,
+		Jail:      "backend = systemd",
+	}}}
+	problems := twice.jailProblems()
+	if len(problems) != 1 || !strings.Contains(problems[0], "names <HOST> 2 times") {
+		t.Fatalf("a pattern naming <HOST> twice was not refused by name: %v", problems)
+	}
+	if !strings.Contains(problems[0], "no bans at all") {
+		t.Errorf("the refusal does not say what it costs: %q", problems[0])
+	}
+
+	// The same two shapes, one pattern each, is how it is written — and is accepted.
+	split := Manifest{Module: "route-proxy", Jails: []Jail{{
+		Name:      "route-proxy",
+		Failregex: "^.*refused for <HOST>:\\d+$\n            ^.*asked from <HOST>:\\d+$",
+		Jail:      "backend = systemd",
+	}}}
+	if problems := split.jailProblems(); len(problems) != 0 {
+		t.Fatalf("one <HOST> per pattern was refused: %v", problems)
+	}
+}
+
+// A jail with no name, no pattern, or a name another jail of the same module already took is refused.
+func TestAJailIsNamedOnceAndSaysWhatAFailureLooksLike(t *testing.T) {
+	m := Manifest{Module: "mailu", Jails: []Jail{
+		{Name: "", Failregex: "^.*rip=<HOST>$"},
+		{Name: "mailu-front", Failregex: "  "},
+		{Name: "mailu-front", Failregex: "^.*rip=<HOST>$"},
+	}}
+	problems := strings.Join(m.jailProblems(), "\n")
+	for _, want := range []string{"a jail with no name", "says nothing a failed attempt looks like", "two jails called"} {
+		if !strings.Contains(problems, want) {
+			t.Errorf("missing %q in:\n%s", want, problems)
+		}
+	}
+}