feat(theme-selector): convert theme.json into a loadable deftheme

build-theme.el is the last link in the theme-selector pipeline: a theme.json export becomes a single self-contained themes/<name>-theme.el. All four tiers convert: default from assignments.bg/.p, the syntax categories to their font-lock/tree-sitter faces with the bold/italic sets applied, UI passthrough, and package faces with :inherit/:height/weight/slant.

The output is a flat generated deftheme, not the palette/faces/theme trio the hand-authored dupre ships. A theme.json carries resolved per-face hex, not dupre's semantic-mapping layer, so a flat deftheme is the faithful output and never clobbers the curated dupre files.

I omitted the dec (decorator) key: Emacs has no dedicated decorator face and renders decorators with font-lock-type-face, which the type key already owns, so coloring dec independently would clobber types. Decorators follow the type color, as they do in stock Emacs.

20 ERT tests cover the attribute builder, each tier, the dec omission, and an end-to-end convert-and-load with a WCAG-AA assertion on the round-tripped default.

1 files changed, 292 insertions, 0 deletions

diff --git a/tests/test-build-theme.el b/tests/test-build-theme.el
new file mode 100644
index 00000000..8624be6b
--- /dev/null
+++ b/tests/test-build-theme.el
@@ -0,0 +1,292 @@
+;;; test-build-theme.el --- Tests for the theme.json -> dupre-*.el converter -*- lexical-binding: t -*-
+
+;;; Commentary:
+
+;; ERT tests for scripts/theme-selector/build-theme.el, the converter that
+;; turns a theme.json exported by the theme-selector into a loadable Emacs
+;; deftheme file.  This is the correctness-sensitive end of the pipeline, so
+;; it is covered Normal / Boundary / Error per category.
+
+;;; Code:
+
+(require 'ert)
+(require 'json)
+
+;; The converter lives under scripts/, not on the normal load-path.  Add it at
+;; compile time too (the validate hook byte-compiles this file in isolation and
+;; only -L's the project, modules, tests, and themes dirs).
+(eval-and-compile
+  (add-to-list 'load-path
+               (expand-file-name
+                "../scripts/theme-selector"
+                (file-name-directory
+                 (or load-file-name
+                     (bound-and-true-p byte-compile-current-file)
+                     buffer-file-name
+                     default-directory)))))
+
+(require 'build-theme)
+
+;;; ---------------------------------------------------------------------------
+;;; Fixtures
+
+(defconst test-build-theme--fixture-json
+  "{
+ \"name\": \"dupre-fixture\",
+ \"palette\": [[\"#000000\",\"ground\"],[\"#7a9abe\",\"blue\"],[\"#84b068\",\"green\"]],
+ \"assignments\": {
+  \"bg\":\"#000000\", \"p\":\"#cdced1\",
+  \"kw\":\"#7a9abe\", \"str\":\"#84b068\", \"cm\":\"#838d97\", \"dec\":\"#e8bd30\"
+ },
+ \"bold\": [\"kw\"],
+ \"italic\": [\"cm\"],
+ \"ui\": {
+  \"region\": {\"fg\":null, \"bg\":\"#264364\"},
+  \"mode-line\": {\"fg\":\"#cdced1\", \"bg\":\"#2f343a\"}
+ },
+ \"packages\": {
+  \"org-mode\": {
+   \"org-level-1\": {\"fg\":\"#67809c\",\"bg\":null,\"bold\":true,\"italic\":false,\"inherit\":null,\"source\":\"default\"},
+   \"org-level-2\": {\"fg\":\"#e8bd30\",\"bg\":null,\"bold\":false,\"italic\":false,\"inherit\":\"org-level-1\",\"height\":1.2,\"source\":\"user\"},
+   \"org-tag\": {\"fg\":null,\"bg\":null,\"bold\":false,\"italic\":false,\"inherit\":null,\"source\":\"cleared\"}
+  }
+ }
+}"
+  "A self-contained theme.json exercising every tier: default, syntax (bold +
+italic + the unmappable dec key), UI, and packages (a plain face, an
+inherit+height face, and a cleared face).  Owned by the test so it can't drift
+the way Craig's downloaded exports under scripts/theme-selector/ can.")
+
+(defun test-build-theme--write-fixture (dir)
+  "Write the fixture JSON into DIR and return its path."
+  (let ((path (expand-file-name "dupre-fixture.json" dir)))
+    (with-temp-file path (insert test-build-theme--fixture-json))
+    path))
+
+(defmacro test-build-theme--with-sandbox (var &rest body)
+  "Bind VAR to a fresh temp directory, run BODY, then delete it."
+  (declare (indent 1))
+  `(let ((,var (make-temp-file "build-theme-test-" t)))
+     (unwind-protect (progn ,@body)
+       (delete-directory ,var t))))
+
+;; --- WCAG contrast helpers (mirror of the dupre-theme test helpers) ---
+
+(defun test-build-theme--channel-luminance (c)
+  "Linearize an 8-bit channel value C (0-255) per the WCAG formula."
+  (let ((x (/ c 255.0)))
+    (if (<= x 0.03928) (/ x 12.92) (expt (/ (+ x 0.055) 1.055) 2.4))))
+
+(defun test-build-theme--relative-luminance (hex)
+  "WCAG relative luminance of HEX color \"#rrggbb\"."
+  (+ (* 0.2126 (test-build-theme--channel-luminance (string-to-number (substring hex 1 3) 16)))
+     (* 0.7152 (test-build-theme--channel-luminance (string-to-number (substring hex 3 5) 16)))
+     (* 0.0722 (test-build-theme--channel-luminance (string-to-number (substring hex 5 7) 16)))))
+
+(defun test-build-theme--contrast (fg bg)
+  "WCAG contrast ratio between hex colors FG and BG."
+  (let ((l1 (test-build-theme--relative-luminance fg))
+        (l2 (test-build-theme--relative-luminance bg)))
+    (/ (+ (max l1 l2) 0.05) (+ (min l1 l2) 0.05))))
+
+;;; ---------------------------------------------------------------------------
+;;; build-theme/--attrs (the core attribute builder)
+
+(ert-deftest test-build-theme-attrs-fg-and-bold ()
+  "Normal: a foreground plus bold yields :foreground and :weight bold."
+  (should (equal (build-theme/--attrs nil "#67809c" nil t nil nil)
+                 '(:foreground "#67809c" :weight bold))))
+
+(ert-deftest test-build-theme-attrs-full-ordering ()
+  "Normal: every attribute present, in canonical order."
+  (should (equal (build-theme/--attrs 'org-level-1 "#e8bd30" "#1a1714" t t 1.3)
+                 '(:inherit org-level-1 :foreground "#e8bd30" :background "#1a1714"
+                            :weight bold :slant italic :height 1.3))))
+
+(ert-deftest test-build-theme-attrs-empty-is-nil ()
+  "Boundary: a fully-cleared face (all nil) yields an empty plist."
+  (should (equal (build-theme/--attrs nil nil nil nil nil nil) '())))
+
+(ert-deftest test-build-theme-attrs-bold-false-omits-weight ()
+  "Boundary: bold false produces no :weight key (only overrides are written)."
+  (should (equal (build-theme/--attrs nil "#cdced1" nil nil nil nil)
+                 '(:foreground "#cdced1"))))
+
+(ert-deftest test-build-theme-attrs-height-one-omitted ()
+  "Boundary: a height of exactly 1.0 is omitted (the default multiplier)."
+  (should (equal (build-theme/--attrs nil "#cdced1" nil nil nil 1.0)
+                 '(:foreground "#cdced1")))
+  (should (equal (build-theme/--attrs nil "#cdced1" nil nil nil 1)
+                 '(:foreground "#cdced1"))))
+
+;;; ---------------------------------------------------------------------------
+;;; build-theme/--face-spec (skips empty faces)
+
+(ert-deftest test-build-theme-face-spec-normal ()
+  "Normal: a face with attrs becomes a custom-theme-set-faces spec."
+  (should (equal (build-theme/--face-spec 'font-lock-string-face '(:foreground "#84b068"))
+                 '(font-lock-string-face ((t (:foreground "#84b068")))))))
+
+(ert-deftest test-build-theme-face-spec-empty-skipped ()
+  "Boundary: a face with no attributes (cleared) yields nil, not an empty spec."
+  (should (null (build-theme/--face-spec 'whatever '()))))
+
+;;; ---------------------------------------------------------------------------
+;;; Syntax tier
+
+(ert-deftest test-build-theme-syntax-keyword-bold ()
+  "Normal: kw maps to font-lock-keyword-face and picks up the bold set."
+  (let* ((assignments '((kw . "#7a9abe") (str . "#84b068")))
+         (specs (build-theme/--syntax-face-specs assignments '(kw) '())))
+    (should (member '(font-lock-keyword-face ((t (:foreground "#7a9abe" :weight bold))))
+                    specs))
+    (should (member '(font-lock-string-face ((t (:foreground "#84b068"))))
+                    specs))))
+
+(ert-deftest test-build-theme-syntax-one-to-many ()
+  "Normal: punc fans out to every punctuation/bracket/delimiter face."
+  (let ((specs (build-theme/--syntax-face-specs '((punc . "#a9b2bb")) '() '())))
+    (dolist (face '(font-lock-punctuation-face font-lock-bracket-face
+                    font-lock-delimiter-face font-lock-misc-punctuation-face))
+      (should (member `(,face ((t (:foreground "#a9b2bb")))) specs)))))
+
+(ert-deftest test-build-theme-syntax-decorator-omitted ()
+  "Boundary: dec has no independent Emacs face, so it maps to nothing.
+Emacs renders decorators with font-lock-type-face, which ty already owns;
+mapping dec would clobber the type color."
+  (let ((specs (build-theme/--syntax-face-specs '((dec . "#e8bd30")) '() '())))
+    (should (null specs))))
+
+(ert-deftest test-build-theme-syntax-comment-italic ()
+  "Normal: cm in the italic set yields :slant italic on the comment face."
+  (let ((specs (build-theme/--syntax-face-specs '((cm . "#a9b2bb")) '() '(cm))))
+    (should (member '(font-lock-comment-face ((t (:foreground "#a9b2bb" :slant italic))))
+                    specs))))
+
+;;; ---------------------------------------------------------------------------
+;;; Default face
+
+(ert-deftest test-build-theme-default-face ()
+  "Normal: default takes background from bg and foreground from p."
+  (should (equal (build-theme/--default-spec '((bg . "#000000") (p . "#cdced1")))
+                 '(default ((t (:foreground "#cdced1" :background "#000000")))))))
+
+;;; ---------------------------------------------------------------------------
+;;; UI tier
+
+(ert-deftest test-build-theme-ui-passthrough ()
+  "Normal: a ui face passes fg/bg straight through."
+  (let ((specs (build-theme/--ui-face-specs
+                '((region . ((fg . nil) (bg . "#264364")))
+                  (mode-line . ((fg . "#cdced1") (bg . "#2f343a")))))))
+    (should (member '(region ((t (:background "#264364")))) specs))
+    (should (member '(mode-line ((t (:foreground "#cdced1" :background "#2f343a")))) specs))))
+
+;;; ---------------------------------------------------------------------------
+;;; Package tier
+
+(ert-deftest test-build-theme-package-inherit-and-height ()
+  "Normal: a package face writes :inherit plus overrides plus :height."
+  (let ((specs (build-theme/--package-face-specs
+                '((org-mode . ((org-level-2 . ((fg . "#e8bd30") (bg . nil)
+                                               (bold . nil) (italic . nil)
+                                               (inherit . "org-level-1") (height . 1.2)
+                                               (source . "user")))))))))
+    (should (member '(org-level-2 ((t (:inherit org-level-1 :foreground "#e8bd30" :height 1.2))))
+                    specs))))
+
+(ert-deftest test-build-theme-package-cleared-skipped ()
+  "Boundary: a cleared package face (no renderable attrs) is not emitted."
+  (let ((specs (build-theme/--package-face-specs
+                '((org-mode . ((org-tag . ((fg . nil) (bg . nil) (bold . nil)
+                                           (italic . nil) (inherit . nil)
+                                           (height . nil) (source . "cleared")))))))))
+    (should (null specs))))
+
+;;; ---------------------------------------------------------------------------
+;;; Hex validation
+
+(ert-deftest test-build-theme-hex-p ()
+  "Normal/Error: only #rrggbb strings validate."
+  (should (build-theme/--hex-p "#0d0b0a"))
+  (should (build-theme/--hex-p "#FFFFFF"))
+  (should-not (build-theme/--hex-p "0d0b0a"))
+  (should-not (build-theme/--hex-p "#fff"))
+  (should-not (build-theme/--hex-p nil)))
+
+;;; ---------------------------------------------------------------------------
+;;; End-to-end: convert a file and load the result
+
+(ert-deftest test-build-theme-convert-file-writes-loadable-theme ()
+  "Integration: converting the fixture produces a theme Emacs can load.
+Components integrated:
+- build-theme/convert-file (entry point, real)
+- json parsing of the inline fixture (real)
+- custom-theme-set-faces / load-theme (real)
+Validates the syntax, default, UI, and package tiers all reach real faces,
+including an inherit+height package face."
+  (require 'org)
+  (test-build-theme--with-sandbox out
+    (let* ((in (test-build-theme--write-fixture out))
+           (path (build-theme/convert-file in out)))
+      (should (file-exists-p path))
+      (should (string-suffix-p "dupre-fixture-theme.el" path))
+      (let ((custom-theme-load-path (cons out custom-theme-load-path))
+            (load-path (cons out load-path)))
+        (unwind-protect
+            (progn
+              (load-theme 'dupre-fixture t)
+              ;; default tier
+              (should (string= (face-attribute 'default :background nil t) "#000000"))
+              (should (string= (face-attribute 'default :foreground nil t) "#cdced1"))
+              ;; syntax tier (kw is blue + bold in the fixture)
+              (should (string= (face-attribute 'font-lock-keyword-face :foreground nil t) "#7a9abe"))
+              (should (eq (face-attribute 'font-lock-keyword-face :weight nil t) 'bold))
+              ;; ui tier
+              (should (string= (face-attribute 'region :background nil t) "#264364"))
+              ;; package tier — plain face and an inherit+height face
+              (should (string= (face-attribute 'org-level-1 :foreground nil t) "#67809c"))
+              (should (eq (face-attribute 'org-level-2 :inherit nil t) 'org-level-1))
+              (should (= (face-attribute 'org-level-2 :height nil t) 1.2)))
+          (disable-theme 'dupre-fixture))))))
+
+(ert-deftest test-build-theme-convert-file-old-json-without-packages ()
+  "Boundary: a theme.json with no packages key still converts and loads."
+  (test-build-theme--with-sandbox out
+    (let* ((json "{\"name\":\"noformat\",\"palette\":[[\"#000000\",\"ground\"]],\"assignments\":{\"bg\":\"#000000\",\"p\":\"#ffffff\",\"kw\":\"#67809c\"},\"bold\":[\"kw\"],\"italic\":[],\"ui\":{}}")
+           (in (expand-file-name "noformat.json" out)))
+      (with-temp-file in (insert json))
+      (let ((path (build-theme/convert-file in out)))
+        (should (file-exists-p path))
+        (let ((custom-theme-load-path (cons out custom-theme-load-path))
+              (load-path (cons out load-path)))
+          (unwind-protect
+              (progn
+                (load-theme 'noformat t)
+                (should (string= (face-attribute 'default :background nil t) "#000000"))
+                (should (string= (face-attribute 'font-lock-keyword-face :foreground nil t) "#67809c")))
+            (disable-theme 'noformat)))))))
+
+(ert-deftest test-build-theme-convert-file-missing-input-errors ()
+  "Error: a missing input file signals rather than writing garbage."
+  (test-build-theme--with-sandbox out
+    (should-error (build-theme/convert-file (expand-file-name "does-not-exist.json" out) out))))
+
+(ert-deftest test-build-theme-generated-default-meets-wcag-aa ()
+  "Error/Regression: the generated default face stays legible.
+A WCAG-AA (>= 4.5:1) assertion on the round-tripped result -- proves the whole
+parse -> spec -> file -> face pipeline preserves the designed contrast."
+  (test-build-theme--with-sandbox out
+    (let ((path (build-theme/convert-file (test-build-theme--write-fixture out) out)))
+      (let ((custom-theme-load-path (cons out custom-theme-load-path))
+            (load-path (cons out load-path)))
+        (unwind-protect
+            (progn
+              (load-theme 'dupre-fixture t)
+              (let ((fg (face-attribute 'default :foreground nil t))
+                    (bg (face-attribute 'default :background nil t)))
+                (should (>= (test-build-theme--contrast fg bg) 4.5))))
+          (disable-theme 'dupre-fixture))))))
+
+(provide 'test-build-theme)
+;;; test-build-theme.el ends here