Tests: a repeat iteration renders in no group, a group that names nothing is refused, a group name is local to its category, and one overlap verdict wherever the reads sit

inline_test.go

@@ -108,8 +108,9 @@ func TestFakeTemplateErrors(t *testing.T) {
 		{`name: {/no.such.path}`, "no entry"},
 		{`name: {..nope}`, "write {/nope}"},
 		{`{"format":"x"}`, "is a string"},
-		{`{/misc.country} {/misc.country.alpha2}`, "renders a level"},
+		{`{/misc.country} {/misc.country.alpha2}`, "renders a level that {/misc.country.alpha2} reads a path into; name the fields you want instead, or draw them apart with a group"},
 		{`{"format":"{/misc.country.alpha2} {x}","x":"{/misc.country}"}`, "reads a path into"},
+		{`{"format":"{/misc.country.alpha2}","group":"g"}`, "nothing can reference"},
 	} {
 		_, err := f.FakeTemplate(c.input)
 		if err == nil || !strings.Contains(err.Error(), c.want) {