1 files changed, 63 insertions, 0 deletions
diff --git a/tests/test-music-config--bar-fill.el b/tests/test-music-config--bar-fill.el
new file mode 100644
index 00000000..f6d8dac8
--- /dev/null
+++ b/tests/test-music-config--bar-fill.el
@@ -0,0 +1,63 @@
+;;; test-music-config--bar-fill.el --- Tests for progress-bar fill math -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; Unit tests for `cj/music--bar-fill': the pure computation of how many cells
+;; of a WIDTH-cell progress bar are filled given ELAPSED and TOTAL seconds.
+;; A stream (no duration) is indeterminate; the live elapsed source (mpv) is
+;; wired in a later phase, so this helper only does the clamp-and-round math.
+;;
+;;; Code:
+
+(require 'ert)
+
+(defvar-keymap cj/custom-keymap :doc "Stub keymap for testing")
+
+(let ((emms-dir (car (file-expand-wildcards
+                      (expand-file-name "elpa/emms-*" user-emacs-directory)))))
+  (when emms-dir (add-to-list 'load-path emms-dir)))
+
+(require 'emms)
+(require 'music-config)
+
+;;; Normal
+
+(ert-deftest test-music-config--bar-fill-normal-half ()
+  "Normal: halfway through fills half the cells."
+  (should (= (cj/music--bar-fill 30 60 20) 10)))
+
+(ert-deftest test-music-config--bar-fill-normal-quarter ()
+  "Normal: a quarter elapsed rounds to a quarter of the cells."
+  (should (= (cj/music--bar-fill 15 60 20) 5)))
+
+;;; Boundary
+
+(ert-deftest test-music-config--bar-fill-boundary-zero-elapsed ()
+  "Boundary: nothing elapsed fills no cells."
+  (should (= (cj/music--bar-fill 0 60 20) 0)))
+
+(ert-deftest test-music-config--bar-fill-boundary-full ()
+  "Boundary: elapsed equal to total fills every cell."
+  (should (= (cj/music--bar-fill 60 60 20) 20)))
+
+(ert-deftest test-music-config--bar-fill-boundary-over-clamps ()
+  "Boundary: elapsed past total clamps to full, never overflows."
+  (should (= (cj/music--bar-fill 90 60 20) 20)))
+
+(ert-deftest test-music-config--bar-fill-boundary-nil-elapsed ()
+  "Boundary: an unknown elapsed (nil) fills no cells."
+  (should (= (cj/music--bar-fill nil 60 20) 0)))
+
+;;; Error / indeterminate
+
+(ert-deftest test-music-config--bar-fill-indeterminate-nil-total ()
+  "Error: a stream (nil total) is indeterminate, not a cell count."
+  (should (eq (cj/music--bar-fill 30 nil 20) 'indeterminate)))
+
+(ert-deftest test-music-config--bar-fill-indeterminate-zero-total ()
+  "Error: a zero total is indeterminate rather than a divide-by-zero."
+  (should (eq (cj/music--bar-fill 30 0 20) 'indeterminate)))
+
+(provide 'test-music-config--bar-fill)
+;;; test-music-config--bar-fill.el ends here