Plan independent BFF and adapt selected Sendico foundations (#34)

backend/internal/evidence/key_test.go

@@ -0,0 +1,18 @@
+package evidence
+
+import "testing"
+
+func TestKeyConfinement(t *testing.T) {
+	for _, ref := range []string{"", ".", "..", "../other", "/other", "a/../../other", "a\\..\\other", "%2e%2e/other", "bad\x00key"} {
+		if _, err := JoinKey("customer/documents", ref); err == nil {
+			t.Errorf("accepted %q", ref)
+		}
+		if _, err := JoinKey(ref, "document"); err == nil {
+			t.Errorf("accepted prefix %q", ref)
+		}
+	}
+	got, err := JoinKey("customer/documents/", "passport/front")
+	if err != nil || got != "customer/documents/passport/front" {
+		t.Fatalf("got %q, %v", got, err)
+	}
+}