content tests are three-valued: unknown when unreadable or read in part

1 files changed, 30 insertions, 3 deletions

diff --git a/internal/cond/eval_test.go b/internal/cond/eval_test.go
index 2e8bcfd..7d796a1 100644
--- a/internal/cond/eval_test.go
+++ b/internal/cond/eval_test.go
@@ -167,11 +167,11 @@ func TestExplainFormat(t *testing.T) {
 	c, _ := Compile("d.conf", nodes(t, `(type pdf) (or (content "acme ltd") (name "\bacme\b"))`), Options{IgnoreCase: true})
 	var b strings.Builder
 	c.Explain(f).Format(&b)
-	want := "no   and\n" +
+	want := "?    and\n" +
 		"yes    type pdf\n" +
-		"no     or\n" +
+		"?      or\n" +
 		"no       name \"\\bacme\\b\"\n" +
-		"no       content \"acme ltd\"  (content unreadable: needs pdftotext, not installed)\n"
+		"?        content \"acme ltd\"  (content unreadable: needs pdftotext, not installed)\n"
 	if b.String() != want {
 		t.Fatalf("got\n%s\nwant\n%s", b.String(), want)
 	}
@@ -257,3 +257,30 @@ func TestCapturesKeepDiacritics(t *testing.T) {
 		t.Errorf("captures with a group that did not take part = %q, want %q", r.Captures, want)
 	}
 }
+
+// TestUnreadableContentIsUnknown: a content test that cannot read the file
+// is unknown, not false, and and/or/not combine unknowns the way Kleene's
+// three-valued logic does: a condition certainly false (or true) whatever
+// the text holds is decided, and only one that depends on the text is
+// unknown (plan 11, re-review cache F2). A rule matches only a true
+// condition; an exclude holds on true or unknown.
+func TestUnreadableContentIsUnknown(t *testing.T) {
+	f := &fake{name: "a.pdf", rawErr: errors.New("larger than max-read")}
+	cases := []struct {
+		src               string
+		match, unreadable bool
+	}{
+		{`(and (content "x") (type txt))`, false, false},
+		{`(or (content "x") (type pdf))`, true, false},
+		{`(not (content "x"))`, false, true},
+		{`(and (type pdf) (content "x"))`, false, true},
+		{`(or (type txt) (content "x"))`, false, true},
+		{`(content "secret") (and (content "other") (type txt))`, false, false},
+		{`(not (and (content "x") (type txt)))`, true, false},
+	}
+	for _, c := range cases {
+		if r := eval(t, c.src, Options{}, f); r.Match != c.match || r.Unreadable != c.unreadable {
+			t.Errorf("%s: Match %v Unreadable %v; want %v, %v", c.src, r.Match, r.Unreadable, c.match, c.unreadable)
+		}
+	}
+}