talk/internal/langdetect/detect_test.go

package langdetect

import "testing"

// TestDetect is table-driven: input text, expected language. The fallback
// applies to empty, undecidable and tied text; it is passed explicitly so
// the test pins both directions.
func TestDetect(t *testing.T) {
	cases := []struct {
		name     string
		text     string
		fallback string
		want     string
	}{
		{"empty → fallback de", "", "de", "de"},
		{"empty → fallback en", "", "en", "en"},
		{"whitespace only", "   \n\t ", "en", "en"},
		{"punctuation only", "!!! ??? ...", "de", "de"},
		{"german sentence", "Der Build wurde erfolgreich abgeschlossen und das Deployment ist fertig.", "en", "de"},
		{"undecidable german question → fallback", "Was macht er?", "en", "en"},
		{"german umlauts", "Größe früh Ärzteübung — schön daß es klappt", "en", "de"},
		{"ß alone", "weiß", "en", "de"},
		{"english sentence", "The build has finished and the deployment is done.", "de", "en"},
		{"english imperative", "Please wait until the tests are green.", "de", "en"},
		{"english single word", "done", "de", "en"},
		{"mixed, english dominates", "the build is done and ready for you", "de", "en"},
		{"mixed, german dominates", "Der build ist done und fertig für dich", "en", "de"},
		{"tie → fallback", "der the", "en", "en"},
		{"undecidable → fallback", "Build 2026-10-18 14:22 UTC", "de", "de"},
		{"agent-style en", "Task completed. Please review the changes and approve.", "de", "en"},
		{"agent-style de", "Aufgabe abgeschlossen. Bitte prüfen und freigeben.", "en", "de"},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			if got := Detect(tc.text, tc.fallback); got != tc.want {
				t.Errorf("Detect(%q, %q) = %q, want %q", tc.text, tc.fallback, got, tc.want)
			}
		})
	}
}