Taxonomy: Add comprehensive unit tests for sanitize_term()

Adds a new test suite for sanitize_term() to ensure coverage of:
- Sanitizing both objects and arrays.
- Handling missing term_id correctly.
- Applying different sanitization contexts (raw, edit, display, attribute, js).
- Verifying field sanitization results in each context.
- Resolves PHPStan type-checking issues with proper assertions.

Co-authored-by: gemini-cli <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: westonruter

tests/phpunit/tests/term/sanitizeTerm.php

@@ -0,0 +1,122 @@
+<?php
+
+/**
+ * @group taxonomy
+ *
+ * @covers ::sanitize_term
+ */
+class Tests_Term_SanitizeTerm extends WP_UnitTestCase {
+
+	/**
+	 * Tests sanitize_term() inputs and outputs.
+	 *
+	 * @ticket 64238
+	 * @dataProvider data_sanitize_term
+	 *
+	 * @param Closure(): (object|array<string, mixed>) $input_callback       Callback to get the term data.
+	 * @param string                                   $context              Context in which to sanitize the term.
+	 * @param string                                   $expected_description Expected sanitized description.
+	 */
+	public function test_sanitize_term( Closure $input_callback, string $context, string $expected_description ): void {
+		$input    = $input_callback();
+		$taxonomy = 'category';
+
+		$sanitized = sanitize_term( $input, $taxonomy, $context );
+
+		if ( is_object( $input ) ) {
+			$this->assertInstanceOf( stdClass::class, $sanitized );
+			$this->assertSame( $context, $sanitized->filter );
+			if ( isset( $input->description ) ) {
+				$this->assertSame( $expected_description, $sanitized->description );
+			}
+		} else {
+			$this->assertIsArray( $sanitized );
+			$this->assertSame( $context, $sanitized['filter'] );
+			if ( isset( $input['description'] ) ) {
+				$this->assertSame( $expected_description, $sanitized['description'] );
+			}
+		}
+	}
+
+	/**
+	 * Data provider for test_sanitize_term.
+	 *
+	 * @return array<string, array{
+	 *     input_callback: Closure(): (object|array<string, mixed>),
+	 *     context: string,
+	 *     expected_description: string,
+	 * }>
+	 */
+	public function data_sanitize_term(): array {
+		$description = 'Test <script>document.write("Hello")</script> Description';
+
+		return array(
+			'Object with term_id, edit context'    => array(
+				'input_callback'       => fn() => (object) array(
+					'term_id'     => 123,
+					'name'        => 'Test Term',
+					'description' => $description,
+				),
+				'context'              => 'edit',
+				'expected_description' => esc_html( $description ),
+			),
+			'Object without term_id, edit context' => array(
+				'input_callback'       => fn() => (object) array(
+					'name'        => 'Test Term',
+					'description' => $description,
+				),
+				'context'              => 'edit',
+				'expected_description' => esc_html( $description ),
+			),
+			'Array with term_id, edit context'     => array(
+				'input_callback'       => fn() => array(
+					'term_id'     => 123,
+					'name'        => 'Test Term',
+					'description' => $description,
+				),
+				'context'              => 'edit',
+				'expected_description' => esc_html( $description ),
+			),
+			'Array without term_id, edit context'  => array(
+				'input_callback'       => fn() => array(
+					'name'        => 'Test Term',
+					'description' => $description,
+				),
+				'context'              => 'edit',
+				'expected_description' => esc_html( $description ),
+			),
+			'Raw context'                          => array(
+				'input_callback'       => fn() => (object) array(
+					'term_id'     => 123,
+					'description' => $description,
+				),
+				'context'              => 'raw',
+				'expected_description' => $description,
+			),
+			'Display context'                      => array(
+				'input_callback'       => fn() => (object) array(
+					'term_id'     => 123,
+					'description' => $description,
+				),
+				'context'              => 'display',
+				'expected_description' => "<p>$description</p>\n",
+			),
+			'Attribute context'                    => array(
+				'input_callback'       => fn() => (object) array(
+					'term_id'     => 123,
+					'description' => $description,
+				),
+				'context'              => 'attribute',
+				'expected_description' => esc_attr( "<p>$description</p>\n" ),
+			),
+			'JS context'                           => array(
+				'input_callback'       => fn() => (object) array(
+					'term_id'     => 123,
+					'description' => $description,
+				),
+				'context'              => 'js',
+				'expected_description' => esc_js( "<p>$description</p>\n" ),
+			),
+		);
+	}
+}