Add some tests for history

tools/tui/readline/actions.go

@@ -42,7 +42,9 @@ func (self *Readline) text_after_cursor_pos() string {
 		}
 	}
 	ans := buf.String()
-	ans = ans[:len(ans)-1]
+	if ans != "" {
+		ans = ans[:len(ans)-1]
+	}
 	return ans
 }
 
@@ -465,6 +467,9 @@ func (self *Readline) yank(repeat_count uint, pop bool) bool {
 
 func (self *Readline) apply_history_text(text string) {
 	self.lines = utils.Splitlines(text)
+	if len(self.lines) == 0 {
+		self.lines = []string{""}
+	}
 }
 
 func (self *Readline) history_first() bool {

tools/tui/readline/actions_test.go

@@ -373,3 +373,51 @@ func TestEraseChars(t *testing.T) {
 		rl.erase_between(Position{X: 1}, Position{X: 2, Y: 2})
 	}, "", "oree")
 }
+
+func TestHistory(t *testing.T) {
+	lp, _ := loop.New()
+	rl := New(lp, RlInit{Prompt: "$$ "})
+
+	add_item := func(x string) {
+		rl.history.AddItem(x, 0)
+	}
+	add_item("a one")
+	add_item("a two")
+	add_item("b three")
+	add_item("b four")
+
+	test := func(ac Action, before_cursor, after_cursor string) {
+		rl.perform_action(ac, 1)
+		if diff := cmp.Diff(before_cursor, rl.text_upto_cursor_pos()); diff != "" {
+			t.Fatalf("The text before the cursor was not as expected for action: %#v\n%s", ac, diff)
+		}
+		if diff := cmp.Diff(after_cursor, rl.text_after_cursor_pos()); diff != "" {
+			t.Fatalf("The text after the cursor was not as expected for action: %#v\n%s", ac, diff)
+		}
+	}
+
+	test(ActionHistoryPrevious, "", "b four")
+	test(ActionHistoryPrevious, "", "b three")
+	test(ActionHistoryPrevious, "", "a two")
+	test(ActionHistoryPrevious, "", "a one")
+	test(ActionHistoryPrevious, "", "a one")
+	test(ActionHistoryNext, "", "a two")
+	test(ActionHistoryNext, "", "b three")
+	test(ActionHistoryNext, "", "b four")
+	test(ActionHistoryNext, "", "")
+	test(ActionHistoryNext, "", "")
+
+	test(ActionHistoryPrevious, "", "b four")
+	test(ActionHistoryPrevious, "", "b three")
+	test(ActionHistoryNext, "", "b four")
+
+	rl.ResetText()
+	rl.add_text("a")
+	test(ActionHistoryPrevious, "a", " two")
+	test(ActionHistoryPrevious, "a", " one")
+	test(ActionHistoryPrevious, "a", " one")
+	test(ActionHistoryNext, "a", " two")
+	test(ActionHistoryNext, "a", "")
+	test(ActionHistoryNext, "a", "")
+
+}

tools/tui/readline/history.go

@@ -159,6 +159,7 @@ func NewHistory(path string, max_items int) *History {
 func (self *History) FindPrefixMatches(prefix, current_command string) *HistoryMatches {
 	ans := HistoryMatches{items: make([]HistoryItem, 0, len(self.items)+1), prefix: prefix}
 	if prefix == "" {
+		ans.items = ans.items[:len(self.items)]
 		copy(ans.items, self.items)
 	} else {
 		for _, x := range self.items {