Test a declared datatype over a column read, repeats counting as written, null alone on stdin, one leading slash, and the CLI's lone reference against the grammar

cmd/fejkdata/lone_test.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/larvit/fejkdata/internal/grammar"
+)
+
+// grammarLoneReference is the path a format reads when the grammar parses it as one path
+// read of one reference from the root, and nothing else.
+func grammarLoneReference(text string) (string, bool) {
+	toks, err := grammar.ParseFormat(text)
+	if err != nil || len(toks) != 1 || toks[0].Kind != grammar.PathRead || len(toks[0].Arms) != 1 {
+		return "", false
+	}
+	sigil, path, err := grammar.RefShape(toks[0].Arms[0])
+	if err != nil || sigil != "/" {
+		return "", false
+	}
+	return path, true
+}
+
+func TestLoneReferenceAgreesWithTheGrammar(t *testing.T) {
+	for _, text := range []string{
+		"{/sv_SE.person}",
+		"{/misc.currency[US Dollar (Next day)]}",
+		"{/t[a as b].c}",
+		"{/t[f(x)]}",
+		"{/a}{/b}",
+		"{/x}}",
+		"{/}",
+		"{/.x}",
+		" {/x}",
+		"{/a|/b}",
+		"{/x as p}",
+		"{//x}",
+		"{/x(1)}",
+		"{.x}",
+		"x",
+	} {
+		path, lone := loneReference(text)
+		want, wantLone := grammarLoneReference(text)
+		if lone != wantLone || path != want {
+			t.Errorf("loneReference(%q) = %q, %v; the grammar reads %q, %v", text, path, lone, want, wantLone)
+		}
+	}
+}

cmd/fejkdata/main_test.go

@@ -249,6 +249,7 @@ func TestRunTakesNoOperand(t *testing.T) {
 		want string
 	}{
 		{[]string{"sv_SE.person"}, "echo '{/sv_SE.person}' | fejkdata"},
+		{[]string{"/en_US.address"}, "echo '{/en_US.address}' | fejkdata"},
 		{[]string{"{/en_US.person}"}, "echo '{/en_US.person}' | fejkdata"},
 		{[]string{"name: {/sv_SE.person.last}"}, "echo 'name: {/sv_SE.person.last}' | fejkdata"},
 		{[]string{"geo.US.locality[O'Fallon].name"}, `echo '{/geo.US.locality[O'\''Fallon].name}' | fejkdata`},
@@ -494,6 +495,8 @@ func TestRunTemplateMisuse(t *testing.T) {
 		"42":                    "number",
 		"42\n":                  "number",
 		"true\n":                "boolean",
+		"null\n":                "only null",
+		" null ":                "only null",
 		"{//sv_SE.person}":      "write {/sv_SE.person}",
 	} {
 		code, out, errb := runOut(stdin, "--seed", "1")