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Blocking assets: treat non-cacheable and zero-size responses as error… #2418

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Blocking assets: treat non-cacheable and zero-size responses as error… #2418

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Blocking assets: treat non-cacheable and zero-size responses as error…
tejas0306 Mar 17, 2026
1d52c9c
Merge branch 'trunk' into fix/blocking-assets-non-cacheable-and-zero-…
tejas0306 Mar 23, 2026
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27 changes: 24 additions & 3 deletions plugins/performance-lab/includes/site-health/audit-enqueued-assets/helper.php
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Original file line number Diff line number Diff line change
Expand Up @@ -522,9 +522,30 @@ function perflab_aea_get_asset_size( string $resource_url ) {
);
}

// TODO: A non-cacheable response should also be considered an error.
// TODO: A size of zero could be considered an error too.
return strlen( wp_remote_retrieve_body( $response ) );
$body = wp_remote_retrieve_body( $response );
if ( 0 === strlen( $body ) ) {
return new WP_Error(
'zero_size',
__( 'The asset returned an empty response (0 bytes).', 'performance-lab' )
);
}

$cache_control = wp_remote_retrieve_header( $response, 'Cache-Control' );
if ( is_string( $cache_control ) && ( false !== stripos( $cache_control, 'no-store' ) || false !== stripos( $cache_control, 'no-cache' ) ) ) {
return new WP_Error(
'non_cacheable',
wp_kses(
sprintf(
/* translators: %s is the Cache-Control header value */
__( 'The asset is not cacheable (<code>Cache-Control: %s</code>), which can harm performance.', 'performance-lab' ),
esc_html( $cache_control )
),
array( 'code' => array() )
)
);
}

return strlen( $body );
}

/**
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37 changes: 36 additions & 1 deletion ...ab/tests/includes/site-health/audit-enqueued-assets/test-audit-enqueued-assets-helper.php
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Original file line number Diff line number Diff line change
Expand Up @@ -520,10 +520,45 @@ public function test_perflab_aea_get_asset_size(): void {

$this->assertWPError( perflab_aea_get_asset_size( 'https://example.com/script1.js' ) );
$this->assertWPError( perflab_aea_get_asset_size( 'https://example.com/script2.js' ) );
$this->assertEquals( 0, perflab_aea_get_asset_size( 'https://example.com/script3.js' ) );

$zero_size_result = perflab_aea_get_asset_size( 'https://example.com/script3.js' );
$this->assertWPError( $zero_size_result );
$this->assertSame( 'zero_size', $zero_size_result->get_error_code() );

$this->assertEquals( 1000, perflab_aea_get_asset_size( 'https://example.com/script4.js' ) );
}

/**
* Tests perflab_aea_get_asset_size() returns error for non-cacheable Cache-Control header.
*
* @covers ::perflab_aea_get_asset_size
*/
public function test_perflab_aea_get_asset_size_non_cacheable(): void {
add_filter(
'pre_http_request',
static function ( $preempt, $parsed_args, $url ) {
if ( 'https://example.com/nocache.js' !== $url ) {
return $preempt;
}
return array(
'headers' => new WpOrg\Requests\Utility\CaseInsensitiveDictionary( array( 'Cache-Control' => 'no-store' ) ),
'body' => 'var x = 1;',
'response' => array(
'code' => 200,
'message' => 'OK',
),
);
},
10,
3
);

$result = perflab_aea_get_asset_size( 'https://example.com/nocache.js' );
$this->assertWPError( $result );
$this->assertSame( 'non_cacheable', $result->get_error_code() );
$this->assertStringContainsString( 'no-store', $result->get_error_message() );
}

/**
* Tests perflab_aea_copy_basic_auth_headers() with various scenarios.
*
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