descr-text: add `describe-char-eldoc' describing character at point

* lisp/descr-text.el (describe-char-eldoc): New function returning
basic Unicode codepoint information (e.g. name) about character
at point.  It is meant to be used as a default value of the
`eldoc-documentation-function' variable.
(describe-char-eldoc--format, describe-char-eldoc--truncate):
New helper functions for `describe-char-eldoc' function.

* tests/automated/descr-text-test.el: New file with tests for
`describe-char-eldoc--truncate', `describe-char-eldoc--format',
and `describe-char-eldoc'.

1 files changed, 94 insertions, 0 deletions

diff --git a/test/automated/descr-text-test.el b/test/automated/descr-text-test.el
new file mode 100644
index 00000000000..81ae727f076
--- /dev/null
+++ b/test/automated/descr-text-test.el
@@ -0,0 +1,94 @@
+;;; descr-text-test.el --- ERT tests for descr-text.el -*- lexical-binding: t -*-
+
+;; Copyright (C) 2014 Free Software Foundation, Inc.
+
+;; Author:     Michal Nazarewicz <mina86@mina86.com>
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This package defines regression tests for the descr-text package.
+
+;;; Code:
+
+(require 'ert)
+(require 'descr-text)
+
+
+(ert-deftest descr-text-test-truncate ()
+  "Tests describe-char-eldoc--truncate function."
+  (should (equal ""
+                 (describe-char-eldoc--truncate " \t \n" 100)))
+  (should (equal "foo"
+                 (describe-char-eldoc--truncate "foo" 1)))
+  (should (equal "foo..."
+                 (describe-char-eldoc--truncate "foo wilma fred" 0)))
+  (should (equal "foo..."
+                 (describe-char-eldoc--truncate
+                  "foo wilma fred" (length "foo wilma"))))
+  (should (equal "foo wilma..."
+                 (describe-char-eldoc--truncate
+                  "foo wilma fred" (+ 3 (length "foo wilma")))))
+  (should (equal "foo wilma..."
+                 (describe-char-eldoc--truncate
+                  "foo wilma fred" (1- (length "foo wilma fred")))))
+  (should (equal "foo wilma fred"
+                 (describe-char-eldoc--truncate
+                  "foo wilma fred" (length "foo wilma fred"))))
+  (should (equal "foo wilma fred"
+                 (describe-char-eldoc--truncate
+                  "  foo\t wilma \nfred\t " (length "foo wilma fred")))))
+
+(ert-deftest descr-text-test-format-desc ()
+  "Tests describe-char-eldoc--format function."
+  (should (equal "U+2026: Horizontal ellipsis (Po: Punctuation, Other)"
+                 (describe-char-eldoc--format ?…)))
+  (should (equal "U+2026: Horizontal ellipsis (Punctuation, Other)"
+                 (describe-char-eldoc--format ?… 51)))
+  (should (equal "U+2026: Horizontal ellipsis (Po)"
+                 (describe-char-eldoc--format ?… 40)))
+  (should (equal "Horizontal ellipsis (Po)"
+                 (describe-char-eldoc--format ?… 30)))
+  (should (equal "Horizontal ellipsis"
+                 (describe-char-eldoc--format ?… 20)))
+  (should (equal "Horizontal..."
+                 (describe-char-eldoc--format ?… 10))))
+
+(ert-deftest descr-text-test-desc ()
+  "Tests describe-char-eldoc function."
+  (with-temp-buffer
+    (insert "a…")
+    (goto-char (point-min))
+    (should (eq ?a (following-char))) ; make sure we are where we think we are
+    ;; Function should return nil for an ASCII character.
+    (should (not (describe-char-eldoc)))
+
+    (goto-char (1+ (point)))
+    (should (eq ?… (following-char)))
+    (let ((eldoc-echo-area-use-multiline-p t))
+      ;; Function should return description of an Unicode character.
+      (should (equal "U+2026: Horizontal ellipsis (Po: Punctuation, Other)"
+                     (describe-char-eldoc))))
+
+    (goto-char (point-max))
+    ;; At the end of the buffer, function should return nil and not blow up.
+    (should (not (describe-char-eldoc)))))
+
+
+(provide 'descr-text-test)
+
+;;; descr-text-test.el ends here