1 files changed, 31 insertions, 0 deletions
diff --git a/gui/internal/model/mainconf_test.go b/gui/internal/model/mainconf_test.go
index c77591c..bd7720e 100644
--- a/gui/internal/model/mainconf_test.go
+++ b/gui/internal/model/mainconf_test.go
@@ -167,3 +167,34 @@ func TestMainSettingRefusesAnUnknownHead(t *testing.T) {
 		t.Error("an unknown setting was read")
 	}
 }
+
+// TestClearingASettingKeepsTheRestOfItsLine: clearing removed whole lines,
+// so a setting sharing a line with anything else took it too. The Settings
+// window writes "(defaults\n  (case ignore))" itself - the closing paren of
+// defaults sits on the setting's line - so setting a value and putting it
+// back to "default" broke the file it had just written, and every later
+// change silently reverted.
+func TestClearingASettingKeepsTheRestOfItsLine(t *testing.T) {
+	m, _, _ := mainConf(t, "(include \"dl\")\n")
+	if err := m.SetSetting("case", "ignore"); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.SetSetting("case", ""); err != nil {
+		t.Fatal(err)
+	}
+	if diags := m.Check(); len(diags) > 0 {
+		t.Errorf("the text no longer loads after set-then-clear: %v\n%s", diags[0], m.Text)
+	}
+
+	// The other half: a hand-written one-line (defaults ...).
+	m2, _, _ := mainConf(t, "(include \"dl\")\n(defaults (case ignore) (fold yes))\n")
+	if err := m2.SetSetting("case", ""); err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(m2.Text, "(fold yes)") {
+		t.Errorf("clearing (case ...) took (fold yes) from the same line:\n%s", m2.Text)
+	}
+	if diags := m2.Check(); len(diags) > 0 {
+		t.Errorf("the text no longer loads: %v\n%s", diags[0], m2.Text)
+	}
+}