test(theme-studio): extract color/slug helpers to importable modules and cover them

The pure helpers that were still stranded in app.js — normHex, ratingColor, textOn, and the filename-slug logic — had no unit tests because app.js can't be imported (it runs its bootstrap and references the data placeholders at load). Moved them into importable modules so they can be tested directly: a new app-util.js holds the color/UI-boundary trio, and slugify joins app-core.js. app.js keeps thin wrappers, so no call site changed and the built DOM is byte-identical.

textOn needs rl from colormath, so generate.py's inline strip now drops import lines as well as export lines — app-util.js imports rl for its tests, and the import is stripped on inline where rl is already in the page. _faces in generate.py also gets direct tests for its prefix-strip and label derivation.

New: 12 node tests (normHex, ratingColor, textOn, slugify) and 7 python tests (_faces, app-util integrity, the import strip). Coverage: app-util.js 100/100/100, app-core.js 100/94.9/100, colormath.js 100/96/100 (line/branch/func); generate.py 89% lines (the rest is the __main__ writer and the optional seed-env branch). No bugs surfaced — the logic was correct, just untested.

1 files changed, 16 insertions, 7 deletions

diff --git a/scripts/theme-studio/generate.py b/scripts/theme-studio/generate.py
index 24ad7a1b..56aa5800 100644
--- a/scripts/theme-studio/generate.py
+++ b/scripts/theme-studio/generate.py
@@ -2,15 +2,19 @@ import json, os
 HERE=os.path.dirname(os.path.abspath(__file__))
 
 def strip_exports(src):
-    """Drop ES-module `export` lines so the body loads as a classic <script>.
+    """Drop ES-module `export`/`import` lines so the body loads as a classic <script>.
 
-    A top-level `export` is a syntax error outside a module, so it must go before
-    the body is spliced into the page. test-colormath.mjs applies the identical
-    strip and asserts the page carries the result verbatim (inline-integrity), so
-    the two copies cannot drift. NOTE: this is line-based — the export statement in
-    colormath.js must stay on a single line or the continuation lines survive.
+    A top-level `export` (or `import`) is a syntax error outside a module, so it
+    must go before the body is spliced into the page. Imports are stripped too so a
+    pure module may import a peer for its own unit tests (e.g. app-util.js imports
+    rl from colormath.js) while the inlined copy relies on the peer already being
+    in the page. The .mjs inline-integrity tests apply the identical strip and
+    assert the page carries the result verbatim, so the two copies cannot drift.
+    NOTE: this is line-based — each export/import statement must stay on a single
+    line or the continuation lines survive.
     """
-    return '\n'.join(l for l in src.splitlines() if not l.startswith('export')).rstrip()
+    return '\n'.join(l for l in src.splitlines()
+                     if not (l.startswith('export') or l.startswith('import'))).rstrip()
 
 # Pure color-math core, inlined verbatim into the page so the browser runs the
 # same code the Node tests import (one source of truth).
@@ -25,6 +29,10 @@ APP_BODY=open(os.path.join(HERE,'app.js')).read()
 # Pure package-model + dropdown logic, inlined into the page (and unit-tested via
 # test-app-core.mjs) the same way colormath.js is.
 APP_CORE_BODY=strip_exports(open(os.path.join(HERE,'app-core.js')).read())
+# Pure color/UI-boundary helpers (normHex/ratingColor/textOn), unit-tested via
+# test-app-util.mjs. Its `import rl` line is stripped on inline (rl is already in
+# the page from the colormath core).
+APP_UTIL_BODY=strip_exports(open(os.path.join(HERE,'app-util.js')).read())
 ns={}
 src=open(os.path.join(HERE,'samples.py')).read()
 exec(src[:src.index('cols=')], ns)
@@ -509,6 +517,7 @@ APP_JS</script>"""
 def fill_data(s):
     return (s.replace("COLORMATH_J",COLORMATH_BODY)
      .replace("APP_CORE_J",APP_CORE_BODY)
+     .replace("APP_UTIL_J",APP_UTIL_BODY)
      .replace("SAMPLES_J",json.dumps(SAMPLES))
      .replace("PALETTE_J",json.dumps(PALETTE)).replace("CATS_J",json.dumps(CATS))
      .replace("UIFACES_J",json.dumps(UI_FACES)).replace("UIMAP_J",json.dumps(UIMAP)).replace("APPS_J",json.dumps(APPS))