diff --git a/.circleci/config.yml b/.circleci/config.yml
index f35e1f0..2c919b7 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -39,9 +39,35 @@ jobs:
           INSTALL_SUGGEST: 1
           BEHAT_PROFILE: "--profile=suggest"
 
+  phpunit_tests:
+    <<: *job-build
+    steps:
+      - attach_workspace:
+          at: /workspace
+      - checkout
+      - run: if [ -f "./dev-tools.sh" ] && [ ! "$DEV_TOOLS" ]; then ./dev-tools.sh; fi
+      - setup_remote_docker:
+          docker_layer_caching: true
+      - run: .circleci/build.sh
+      - run:
+          name: Run phpunit tests and generate coverage
+          command: |
+            .circleci/phpunit_tests.sh
+            .circleci/phpunit_coverage.sh
+      - run:
+          name: Copy test results
+          command: |
+            .circleci/phpunit_results.sh
+          when: always
+      - store_artifacts:
+          path: /tmp/phpunit
+      - store_test_results:
+          path: /tmp/phpunit
+
 workflows:
   version: 2
   main:
     jobs:
       - build
       - build_suggest
+      - phpunit_tests
diff --git a/dev-tools.sh b/dev-tools.sh
index d7573df..281696b 100755
--- a/dev-tools.sh
+++ b/dev-tools.sh
@@ -34,5 +34,6 @@
 #
 # Uncomment and set the Dev-Tools's commit value and commit this change.
 # export GH_COMMIT=COMMIT_SHA
+export GH_COMMIT=aefc0a705ec75976acdc8da4e6b89a77047fa307
 
 bash <(curl -L https://raw.githubusercontent.com/dpc-sdp/dev-tools/master/install?"$(date +%s)") "$@"
diff --git a/modules/tide_site_preview/src/Plugin/Block/PreviewLinksBlock.php b/modules/tide_site_preview/src/Plugin/Block/PreviewLinksBlock.php
index 70c8105..5e4cc8c 100644
--- a/modules/tide_site_preview/src/Plugin/Block/PreviewLinksBlock.php
+++ b/modules/tide_site_preview/src/Plugin/Block/PreviewLinksBlock.php
@@ -142,7 +142,12 @@ public function build() {
           if (!empty($sites['sections'][$site_id])) {
             $section = $this->siteHelper->getSiteById($sites['sections'][$site_id]);
           }
-          $preview_urls[$site_id] = $this->sitePreviewHelper->buildFrontendPreviewLink($this->currentNode, $site, $section, $this->getConfiguration());
+          $site_base_url = $this->siteHelper->getSiteBaseUrl($site);
+          $url = $this->currentNode->toUrl('canonical', [
+            'absolute' => TRUE,
+            'base_url' => $site_base_url,
+          ]);
+          $preview_urls[$site_id] = $this->sitePreviewHelper->buildFrontendPreviewLink($this->currentNode, $url, $site, $section, $this->getConfiguration());
         }
       }
     }
@@ -154,7 +159,8 @@ public function build() {
       if (!empty($sites['sections'][$primary_site->id()])) {
         $primary_site_section = $this->siteHelper->getSiteById($sites['sections'][$primary_site->id()]);
       }
-      $primary_preview_url = $this->sitePreviewHelper->buildFrontendPreviewLink($this->currentNode, $primary_site, $primary_site_section, $this->getConfiguration());
+      $url = $this->currentNode->toUrl();
+      $primary_preview_url = $this->sitePreviewHelper->buildFrontendPreviewLink($this->currentNode, $url, $primary_site, $primary_site_section, $this->getConfiguration());
       unset($preview_urls[$primary_site->id()]);
       array_unshift($preview_urls, $primary_preview_url);
     }
diff --git a/modules/tide_site_preview/src/TideSitePreviewHelper.php b/modules/tide_site_preview/src/TideSitePreviewHelper.php
index 3eafc00..cb596f6 100644
--- a/modules/tide_site_preview/src/TideSitePreviewHelper.php
+++ b/modules/tide_site_preview/src/TideSitePreviewHelper.php
@@ -35,6 +35,8 @@ public function __construct(TideSiteHelper $site_helper) {
    *
    * @param \Drupal\node\NodeInterface $node
    *   The node.
+   * @param \Drupal\Core\Url $url
+   *   The url.
    * @param \Drupal\taxonomy\TermInterface $site
    *   The site of the preview link.
    * @param \Drupal\taxonomy\TermInterface|null $section
@@ -49,7 +51,7 @@ public function __construct(TideSiteHelper $site_helper) {
    *   * name: The site/section name.
    *   * url: The absolute URL of the preview link.
    */
-  public function buildFrontendPreviewLink(NodeInterface $node, TermInterface $site, TermInterface $section = NULL, array $configuration = []) : array {
+  public function buildFrontendPreviewLink(NodeInterface $node, Url $url, TermInterface $site, TermInterface $section = NULL, array $configuration = []) : array {
     $url_options = [
       'attributes' => !(empty($configuration['open_new_window'])) ? ['target' => '_blank'] : [],
     ];
@@ -68,7 +70,7 @@ public function buildFrontendPreviewLink(NodeInterface $node, TermInterface $sit
     $site_base_url = $this->siteHelper->getSiteBaseUrl($site);
     if ($node->isPublished() && $node->isDefaultRevision()) {
       unset($url_options['query']['section']);
-      $preview_link['url'] = $this->getNodeFrontendUrl($node, $site_base_url, $url_options);
+      $preview_link['url'] = $this->getNodeFrontendUrl($url, $site_base_url, $url_options);
     }
     else {
       $revision_id = $node->getLoadedRevisionId();
@@ -84,8 +86,8 @@ public function buildFrontendPreviewLink(NodeInterface $node, TermInterface $sit
   /**
    * Get the frontend URL of a node.
    *
-   * @param \Drupal\node\NodeInterface $node
-   *   The node.
+   * @param \Drupal\Core\Url $url
+   *   The url.
    * @param string $site_base_url
    *   The base URL of the frontend.
    * @param array $url_options
@@ -94,19 +96,19 @@ public function buildFrontendPreviewLink(NodeInterface $node, TermInterface $sit
    * @return \Drupal\Core\Url|string
    *   The Url.
    */
-  public function getNodeFrontendUrl(NodeInterface $node, $site_base_url = '', array $url_options = []) {
+  public function getNodeFrontendUrl(Url $url, string $site_base_url = '', array $url_options = []) {
     try {
-      $url = $node->toUrl('canonical', [
-        'absolute' => TRUE,
-        'base_url' => $site_base_url,
-      ] + $url_options);
-
-      $pattern = '/^\/site\-(\d+)\//';
+      $path = $url->toString();
+      $path = rtrim($path, '/');
+      $clean_url = preg_replace('/\/site\-(\d+)\//', '/', $path, 1);
+      if ((strpos($clean_url, '/') !== 0) && (strpos($clean_url, '#') !== 0) && (strpos($clean_url, '?') !== 0)) {
+        return $clean_url ? Url::fromUri($clean_url, $url_options) : $url;
+      }
       if ($site_base_url) {
-        $pattern = '/' . preg_quote($site_base_url, '/') . '\/site\-(\d+)\//';
+        $clean_url = $site_base_url . $clean_url;
+        return $clean_url ? Url::fromUri($clean_url, $url_options) : $url;
       }
-      $clean_url = preg_replace($pattern, $site_base_url . '/', $url->toString());
-      return $clean_url ? Url::fromUri($clean_url, $url_options) : $url;
+      return $clean_url ? Url::fromUserInput($clean_url, $url_options) : $url;
     }
     catch (Exception $exception) {
       watchdog_exception('tide_site_preview', $exception);
diff --git a/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/field.field.taxonomy_term.sites.field_site_domains.yml b/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/field.field.taxonomy_term.sites.field_site_domains.yml
new file mode 100644
index 0000000..fe5a930
--- /dev/null
+++ b/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/field.field.taxonomy_term.sites.field_site_domains.yml
@@ -0,0 +1,18 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.storage.taxonomy_term.field_site_domains
+    - taxonomy.vocabulary.sites
+id: taxonomy_term.sites.field_site_domains
+field_name: field_site_domains
+entity_type: taxonomy_term
+bundle: sites
+label: Domains
+description: 'Please enter domains for this site. One domain per line. Use * as a wildcard.'
+required: true
+translatable: false
+default_value: {  }
+default_value_callback: ''
+settings: {  }
+field_type: string_long
diff --git a/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/field.storage.taxonomy_term.field_site_domains.yml b/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/field.storage.taxonomy_term.field_site_domains.yml
new file mode 100644
index 0000000..df41308
--- /dev/null
+++ b/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/field.storage.taxonomy_term.field_site_domains.yml
@@ -0,0 +1,18 @@
+langcode: en
+status: true
+dependencies:
+  module:
+    - taxonomy
+id: taxonomy_term.field_site_domains
+field_name: field_site_domains
+entity_type: taxonomy_term
+type: string_long
+settings:
+  case_sensitive: false
+module: core
+locked: false
+cardinality: 1
+translatable: true
+indexes: {  }
+persist_with_no_fields: false
+custom_storage: false
diff --git a/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/taxonomy.vocabulary.sites.yml b/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/taxonomy.vocabulary.sites.yml
new file mode 100644
index 0000000..7a113e3
--- /dev/null
+++ b/modules/tide_site_preview/tests/modules/test_tide_site_preview/config/optional/taxonomy.vocabulary.sites.yml
@@ -0,0 +1,8 @@
+langcode: en
+status: true
+dependencies: {  }
+name: Sites
+vid: sites
+description: 'Sites and sections'
+hierarchy: 0
+weight: 0
diff --git a/modules/tide_site_preview/tests/modules/test_tide_site_preview/test_tide_site_preview.info.yml b/modules/tide_site_preview/tests/modules/test_tide_site_preview/test_tide_site_preview.info.yml
new file mode 100644
index 0000000..1c3b01a
--- /dev/null
+++ b/modules/tide_site_preview/tests/modules/test_tide_site_preview/test_tide_site_preview.info.yml
@@ -0,0 +1,4 @@
+name: 'Test tide site preview'
+type: module
+description: 'Support module for tide site preview testing.'
+package: Testing
diff --git a/modules/tide_site_preview/tests/src/Kernel/TideSitePreviewHelperTest.php b/modules/tide_site_preview/tests/src/Kernel/TideSitePreviewHelperTest.php
new file mode 100644
index 0000000..08e7b9c
--- /dev/null
+++ b/modules/tide_site_preview/tests/src/Kernel/TideSitePreviewHelperTest.php
@@ -0,0 +1,194 @@
+<?php
+
+namespace Drupal\Tests\tide_site_preview\Kernel;
+
+use Drupal\Core\Url;
+use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;
+use Drupal\node\Entity\Node;
+use Drupal\taxonomy\Entity\Term;
+
+/**
+ * Tests the TideSitePreviewHelper.
+ *
+ * @coversDefaultClass \Drupal\tide_site_preview\TideSitePreviewHelper
+ * @group tide_site_preview
+ */
+class TideSitePreviewHelperTest extends EntityKernelTestBase {
+
+  /**
+   * The tide_site_preview.helper service.
+   *
+   * @var \Drupal\tide_site_preview\TideSitePreviewHelper
+   */
+  protected $tideSitePreviewHelper;
+
+  /**
+   * The modules to load to run the test.
+   *
+   * @var array
+   */
+  public static $modules = [
+    'tide_site',
+    'tide_site_preview',
+    'node',
+    'taxonomy',
+    'test_tide_site_preview',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->installEntitySchema('node');
+    $this->installEntitySchema('taxonomy_term');
+    $this->installConfig(['tide_site_preview']);
+    $this->installConfig(['test_tide_site_preview']);
+    $this->tideSitePreviewHelper = \Drupal::service('tide_site_preview.helper');
+  }
+
+  /**
+   * @covers ::getNodeFrontendUrl
+   * @dataProvider urlDataProvider
+   */
+  public function testGetNodeFrontendUrl($value, $expected) {
+    $url = Url::fromUri($value);
+    $url = $this->tideSitePreviewHelper->getNodeFrontendUrl($url);
+    $this->assertEquals($expected, $url->toString());
+  }
+
+  /**
+   * Data provider of test dates.
+   *
+   * @return array
+   *   Array of values.
+   */
+  public function urlDataProvider() {
+    return [
+      [
+        'value' => 'https://www.vic.gov.au/site-1/hello_world',
+        'expected' => 'https://www.vic.gov.au/hello_world',
+      ],
+      [
+        'value' => 'https://site-1/hello_world',
+        'expected' => 'https://hello_world',
+      ],
+      [
+        'value' => 'https://site-1/',
+        'expected' => 'https://site-1',
+      ],
+      [
+        'value' => 'https://site-1',
+        'expected' => 'https://site-1',
+      ],
+    ];
+  }
+
+  /**
+   * @covers ::buildFrontendPreviewLink
+   * @dataProvider buildFrontendPreviewLinkDataProvider
+   */
+  public function testBuildFrontendPreviewLink($node_values, $url, $term_values, $config, $expected) {
+    $node = Node::create($node_values);
+    $node->save();
+    $url = Url::fromUserInput($url);
+    $term = Term::create($term_values);
+    $term->save();
+
+    $result = $this->tideSitePreviewHelper->buildFrontendPreviewLink($node, $url, $term, NULL, $config);
+    $url = $result['url']->toString();
+    $this->assertEquals($expected, $url);
+  }
+
+  /**
+   * Data provider of test dates.
+   *
+   * @return array
+   *   Array of values.
+   */
+  public function buildFrontendPreviewLinkDataProvider() {
+    return [
+      [
+        [
+          'type' => 'test',
+          'title' => 'test_1',
+        ],
+        '/site-1/hello_world',
+        [
+          'vid' => 'sites',
+          'name' => 'vicgovau',
+          'field_site_domains' => 'www.vic.gov.au',
+        ],
+        [
+          'id' => 'tide_site_preview_links_block',
+          'label' => 'Click the links below to preview this revision on frontend sites',
+          'provider' => 'tide_site_preview',
+          'label_display' => 'visible',
+          'open_new_window' => 1,
+        ],
+        'https://www.vic.gov.au/hello_world',
+      ],
+      [
+        [
+          'type' => 'test',
+          'title' => 'test_2',
+        ],
+        '/site-2/site-4/hello_world',
+        [
+          'vid' => 'sites',
+          'name' => 'vicgovau',
+          'field_site_domains' => 'www.vic.gov.au',
+        ],
+        [
+          'id' => 'tide_site_preview_links_block',
+          'label' => 'Click the links below to preview this revision on frontend sites',
+          'provider' => 'tide_site_preview',
+          'label_display' => 'visible',
+          'open_new_window' => 1,
+        ],
+        'https://www.vic.gov.au/site-4/hello_world',
+      ],
+      [
+        [
+          'type' => 'test',
+          'title' => 'test_3',
+        ],
+        '/site-3/site-6/site-7/hello_world',
+        [
+          'vid' => 'sites',
+          'name' => 'vicgovau',
+          'field_site_domains' => 'www.vic.gov.au',
+        ],
+        [
+          'id' => 'tide_site_preview_links_block',
+          'label' => 'Click the links below to preview this revision on frontend sites',
+          'provider' => 'tide_site_preview',
+          'label_display' => 'visible',
+          'open_new_window' => 1,
+        ],
+        'https://www.vic.gov.au/site-6/site-7/hello_world',
+      ],
+      [
+        [
+          'type' => 'test',
+          'title' => 'test_4',
+        ],
+        '/site-4/hello_world',
+        [
+          'vid' => 'sites',
+          'name' => 'vicgovau',
+          'field_site_domains' => 'www.vic.gov.au',
+        ],
+        [
+          'id' => 'tide_site_preview_links_block',
+          'label' => 'Click the links below to preview this revision on frontend sites',
+          'provider' => 'tide_site_preview',
+          'label_display' => 'visible',
+          'open_new_window' => 1,
+        ],
+        'https://www.vic.gov.au/hello_world',
+      ],
+    ];
+  }
+
+}