test: remove hardcoded dark palette from tests (#29357)

Issue number: N/A

---------

## What is the current behavior?
Dark palette is hardcoded in style tags in tests. 

## What is the new behavior?

Updated the following tests:
- **datetime/basic** - added an import for `dark.class.css` which works
with the checkbox to toggle the `ion-palette-dark` class
- does not update the e2e test to include dark palette because this was
not tested previously
- **datetime/color** - added an import for `dark.class.css` which works
with the checkbox to toggle the `ion-palette-dark` class
    - updates the e2e test to use the dark palette
- **modal/dark-mode** - added an import for `dark.always.css` which
always applies the dark palette
- does not update the e2e test to include dark palette because this test
needs to be moved but I am not sure where it should go yet
- **toggle/enable-on-off-labels** - added an import for `dark.class.css`
which works with the checkbox to toggle the `ion-palette-dark` class
- updates the e2e test to use the dark palette & splits the color into a
separate screenshot test

Did not update the following tests:
- **item/buttons** - has already been updated to remove the dark palette
- **toggle/legacy/enable-on-off-labels** - test was removed in v8

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

## Other information

- We could probably remove the checkbox toggles entirely when we add
support for the `palette` query param.

---------

Co-authored-by: ionitron <hi@ionicframework.com>

core/src/components/datetime/test/basic/index.html

@@ -5,6 +5,7 @@
     <title>Datetime - Basic</title>
     <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0" />
     <link href="../../../../../css/ionic.bundle.css" rel="stylesheet" />
+    <link href="../../../../../css/palettes/dark.class.css" rel="stylesheet" />
     <link href="../../../../../scripts/testing/styles.css" rel="stylesheet" />
     <script src="../../../../../scripts/testing/scripts.js"></script>
     <script type="module" src="../../../../../dist/ionic/ionic.esm.js"></script>
@@ -49,158 +50,6 @@
       ion-datetime {
         width: 350px;
       }
-
-      body.dark {
-        --ion-color-primary: #428cff;
-        --ion-color-primary-rgb: 66, 140, 255;
-        --ion-color-primary-contrast: #ffffff;
-        --ion-color-primary-contrast-rgb: 255, 255, 255;
-        --ion-color-primary-shade: #3a7be0;
-        --ion-color-primary-tint: #5598ff;
-
-        --ion-color-secondary: #50c8ff;
-        --ion-color-secondary-rgb: 80, 200, 255;
-        --ion-color-secondary-contrast: #ffffff;
-        --ion-color-secondary-contrast-rgb: 255, 255, 255;
-        --ion-color-secondary-shade: #46b0e0;
-        --ion-color-secondary-tint: #62ceff;
-
-        --ion-color-tertiary: #6a64ff;
-        --ion-color-tertiary-rgb: 106, 100, 255;
-        --ion-color-tertiary-contrast: #ffffff;
-        --ion-color-tertiary-contrast-rgb: 255, 255, 255;
-        --ion-color-tertiary-shade: #5d58e0;
-        --ion-color-tertiary-tint: #7974ff;
-
-        --ion-color-success: #2fdf75;
-        --ion-color-success-rgb: 47, 223, 117;
-        --ion-color-success-contrast: #000000;
-        --ion-color-success-contrast-rgb: 0, 0, 0;
-        --ion-color-success-shade: #29c467;
-        --ion-color-success-tint: #44e283;
-
-        --ion-color-warning: #ffd534;
-        --ion-color-warning-rgb: 255, 213, 52;
-        --ion-color-warning-contrast: #000000;
-        --ion-color-warning-contrast-rgb: 0, 0, 0;
-        --ion-color-warning-shade: #e0bb2e;
-        --ion-color-warning-tint: #ffd948;
-
-        --ion-color-danger: #ff4961;
-        --ion-color-danger-rgb: 255, 73, 97;
-        --ion-color-danger-contrast: #ffffff;
-        --ion-color-danger-contrast-rgb: 255, 255, 255;
-        --ion-color-danger-shade: #e04055;
-        --ion-color-danger-tint: #ff5b71;
-
-        --ion-color-dark: #f4f5f8;
-        --ion-color-dark-rgb: 244, 245, 248;
-        --ion-color-dark-contrast: #000000;
-        --ion-color-dark-contrast-rgb: 0, 0, 0;
-        --ion-color-dark-shade: #d7d8da;
-        --ion-color-dark-tint: #f5f6f9;
-
-        --ion-color-medium: #989aa2;
-        --ion-color-medium-rgb: 152, 154, 162;
-        --ion-color-medium-contrast: #000000;
-        --ion-color-medium-contrast-rgb: 0, 0, 0;
-        --ion-color-medium-shade: #86888f;
-        --ion-color-medium-tint: #a2a4ab;
-
-        --ion-color-light: #222428;
-        --ion-color-light-rgb: 34, 36, 40;
-        --ion-color-light-contrast: #ffffff;
-        --ion-color-light-contrast-rgb: 255, 255, 255;
-        --ion-color-light-shade: #1e2023;
-        --ion-color-light-tint: #383a3e;
-      }
-
-      /*
-       * iOS Dark Theme
-       * -------------------------------------------
-       */
-
-      .ios body.dark {
-        --ion-background-color: #000000;
-        --ion-background-color-rgb: 0, 0, 0;
-
-        --ion-text-color: #ffffff;
-        --ion-text-color-rgb: 255, 255, 255;
-
-        --ion-color-step-50: #0d0d0d;
-        --ion-color-step-100: #1a1a1a;
-        --ion-color-step-150: #262626;
-        --ion-color-step-200: #333333;
-        --ion-color-step-250: #404040;
-        --ion-color-step-300: #4d4d4d;
-        --ion-color-step-350: #595959;
-        --ion-color-step-400: #666666;
-        --ion-color-step-450: #737373;
-        --ion-color-step-500: #808080;
-        --ion-color-step-550: #8c8c8c;
-        --ion-color-step-600: #999999;
-        --ion-color-step-650: #a6a6a6;
-        --ion-color-step-700: #b3b3b3;
-        --ion-color-step-750: #bfbfbf;
-        --ion-color-step-800: #cccccc;
-        --ion-color-step-850: #d9d9d9;
-        --ion-color-step-900: #e6e6e6;
-        --ion-color-step-950: #f2f2f2;
-
-        --ion-item-background: #000000;
-
-        --ion-card-background: #1c1c1d;
-      }
-
-      .ios body.dark ion-modal {
-        --ion-background-color: var(--ion-color-step-100);
-        --ion-toolbar-background: var(--ion-color-step-150);
-        --ion-toolbar-border-color: var(--ion-color-step-250);
-        --ion-item-background: var(--ion-color-step-150);
-      }
-
-      /*
-       * Material Design Dark Theme
-       * -------------------------------------------
-       */
-
-      .md body.dark {
-        --ion-background-color: #121212;
-        --ion-background-color-rgb: 18, 18, 18;
-
-        --ion-text-color: #ffffff;
-        --ion-text-color-rgb: 255, 255, 255;
-
-        --ion-border-color: #222222;
-
-        --ion-color-step-50: #1e1e1e;
-        --ion-color-step-100: #2a2a2a;
-        --ion-color-step-150: #363636;
-        --ion-color-step-200: #414141;
-        --ion-color-step-250: #4d4d4d;
-        --ion-color-step-300: #595959;
-        --ion-color-step-350: #656565;
-        --ion-color-step-400: #717171;
-        --ion-color-step-450: #7d7d7d;
-        --ion-color-step-500: #898989;
-        --ion-color-step-550: #949494;
-        --ion-color-step-600: #a0a0a0;
-        --ion-color-step-650: #acacac;
-        --ion-color-step-700: #b8b8b8;
-        --ion-color-step-750: #c4c4c4;
-        --ion-color-step-800: #d0d0d0;
-        --ion-color-step-850: #dbdbdb;
-        --ion-color-step-900: #e7e7e7;
-        --ion-color-step-950: #f3f3f3;
-
-        --ion-item-background: #1e1e1e;
-
-        --ion-toolbar-background: #1f1f1f;
-
-        --ion-tab-bar-background: #1f1f1f;
-
-        --ion-card-background: #1e1e1e;
-      }
     </style>
   </head>
   <body>
@@ -335,12 +184,9 @@ <h2>formatOptions</h2>
 
         const darkModeCheckbox = document.querySelector('ion-checkbox');
         darkModeCheckbox.addEventListener('ionChange', (ev) => {
-          if (ev.detail.checked) {
-            document.body.classList.add('dark');
-          } else {
-            document.body.classList.remove('dark');
-          }
+          document.documentElement.classList.toggle('ion-palette-dark');
         });
+
         color.addEventListener('ionChange', (ev) => {
           datetime.color = ev.target.value;
           buttons.forEach((button) => {

core/src/components/datetime/test/color/datetime.e2e.ts

@@ -4,19 +4,28 @@ import { configs, test } from '@utils/test/playwright';
 /**
  * This behavior does not vary across directions
  */
-configs({ directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
+configs({ directions: ['ltr'], palettes: ['light', 'dark'] }).forEach(({ title, screenshot, config }) => {
   test.describe(title('datetime: color'), () => {
     test('should not have visual regressions', async ({ page }) => {
-      await page.goto('/src/components/datetime/test/color', config);
+      await page.setContent(
+        `
+        <div id="container" style="width: 250px;">
+          <ion-datetime
+            color="danger"
+            value="2022-05-03"
+            show-default-title="true"
+            show-default-buttons="true"
+          ></ion-datetime>
+        </div>
+      `,
+        config
+      );
 
-      const datetime = page.locator('#color-datetime');
+      const container = page.locator('#container');
 
-      await expect(datetime).toHaveScreenshot(screenshot(`datetime-color`));
+      await page.locator('.datetime-ready').waitFor();
 
-      await page.evaluate(() => document.body.classList.toggle('dark'));
-      await page.waitForChanges();
-
-      await expect(datetime).toHaveScreenshot(screenshot(`datetime-color-dark`));
+      await expect(container).toHaveScreenshot(screenshot(`datetime-color`));
     });
   });
 });