Test internal/grammar, and allow the root to import it

internal/grammar/path_test.go

@@ -0,0 +1,40 @@
+package grammar
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestSplitPathKeepsSelectorsAndStepsUpWhole(t *testing.T) {
+	for path, want := range map[string][]string{
+		"a":                       {"a"},
+		"a.b":                     {"a", "b"},
+		"misc.territory[SE].name": {"misc", "territory", "[SE]", "name"},
+		"x[a.b]":                  {"x", "[a.b]"},
+		"city[Oslo]..country":     {"city", "[Oslo]", "..", "country"},
+		"a..b":                    {"a", "..", "b"},
+	} {
+		segs, err := SplitPath(path)
+		if err != nil || !reflect.DeepEqual(segs, want) {
+			t.Errorf("SplitPath(%q) = %q, %v, want %q", path, segs, err, want)
+			continue
+		}
+		if got := JoinSegments(segs); got != path {
+			t.Errorf("JoinSegments(%q) = %q, want %q", segs, got, path)
+		}
+	}
+}
+
+func TestSplitPathRefusesAStraySelectorBracket(t *testing.T) {
+	for _, path := range []string{"[a]", "a.[b]", "a[b", "a]", "a[]", "a[b]c", "a[b[c]]"} {
+		if _, err := SplitPath(path); err == nil {
+			t.Errorf("SplitPath(%q) = nil error, want one", path)
+		}
+	}
+}
+
+func TestNameSegmentsDropSelectorsAndStepsUp(t *testing.T) {
+	if got := NameSegments([]string{"a", "[b]", "..", "c"}); !reflect.DeepEqual(got, []string{"a", "c"}) {
+		t.Errorf("NameSegments = %q, want [a c]", got)
+	}
+}