Chart theming: custom named themes + Theme Builder

src/app/infrastructure/theme-migrations.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, it } from 'vitest';
+import { CURRENT_THEME_VERSION } from '@core/custom-theme';
+import { migrateCustomTheme } from './theme-migrations';
+
+describe('migrateCustomTheme', () => {
+  it('passes a current record through unchanged (plus version stamp)', () => {
+    const record = {
+      id: 3,
+      version: CURRENT_THEME_VERSION,
+      name: 'Brand',
+      config: { font: 'Georgia' },
+      created: '2026-06-12T10:00:00.000Z',
+      modified: '2026-06-12T11:00:00.000Z',
+    };
+    expect(migrateCustomTheme(record)).toEqual(record);
+  });
+
+  it('fills missing or invalid fields with safe defaults', () => {
+    const migrated = migrateCustomTheme({ id: '7', config: ['not', 'an', 'object'] });
+    expect(migrated.id).toBe(7);
+    expect(migrated.version).toBe(CURRENT_THEME_VERSION);
+    expect(migrated.name).toBe('Untitled theme');
+    expect(migrated.config).toEqual({});
+    expect(typeof migrated.created).toBe('string');
+    expect(typeof migrated.modified).toBe('string');
+  });
+
+  it('keeps unknown fields written by a newer build', () => {
+    const migrated = migrateCustomTheme({
+      id: 1,
+      name: 'Next',
+      config: {},
+      futureField: 'kept',
+    });
+    expect((migrated as unknown as Record<string, unknown>).futureField).toBe('kept');
+  });
+});