Tests for a repeated bare token of a held name

bound_test.go

@@ -688,3 +688,27 @@ func TestBoundPathIsReachableByFake(t *testing.T) {
 		}
 	}
 }
+
+func TestRepeatedBareTokenOfAHeldNameIsRejected(t *testing.T) {
+	for src, want := range map[string]string{
+		`{"format":"{w} {w} {uppercase(w)}","w":["a","b"]}`:                                    "write {w} once",
+		`{"format":"{w} {w|x} {uppercase(w)}","w":["a","b"],"x":["c","d"]}`:                    "write {w} once",
+		`{"format":"{n} + {n} = {calc(n * 2)}","n":["1","2"]}`:                                 "write {n} once",
+		`{"format":"{p.a} {q} {q} {lowercase(q)}","p":{"format":"{a}","a":"1"},"q":["A","B"]}`: "write {q} once",
+	} {
+		_, err := compile(parse(t, src))
+		if err == nil || !strings.Contains(err.Error(), want) || !strings.Contains(err.Error(), "holds") {
+			t.Errorf("compile(%s) = %v, want the repeated token rejected naming %s", src, err, want)
+		}
+	}
+	for _, ok := range []string{
+		`{"format":"{w} {w}","w":["a","b"]}`,
+		`{"format":"{w} {uppercase(w)}","w":["a","b"]}`,
+		`{"format":"{net} x {qty} = {calc(net * qty, 2)}","net":["19.99","5.00"],"qty":["3","7"]}`,
+		`{"format":"{uppercase(w)} {uppercase(w)}","w":["a","b"]}`,
+	} {
+		if _, err := compile(parse(t, ok)); err != nil {
+			t.Errorf("compile(%s) = %v, want it accepted", ok, err)
+		}
+	}
+}