diff --git a/.travis.yml b/.travis.yml
index 3558479f8..82e46b706 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,39 +8,29 @@ import:
 
 jobs:
   include:
-    - php: 7.4
+    - php: 7.3
       env:
         - DB=MYSQL
-        - REQUIRE_INSTALLER="4.6.x-dev"
+        - REQUIRE_INSTALLER="4.x-dev"
         - NPM_TEST=1
-    - php: 7.1
-      env:
-        - DB=MYSQL
-        - REQUIRE_INSTALLER="4.6.x-dev"
-        - PHPUNIT_TEST=1
-    - php: 7.2
-      env:
-        - DB=PGSQL
-        - REQUIRE_INSTALLER="4.6.x-dev"
-        - PHPUNIT_TEST=1
     - php: 7.3
       env:
-        - DB=MYSQL
-        - REQUIRE_INSTALLER="4.7.x-dev"
+        - DB=PGSQL
+        - REQUIRE_INSTALLER="4.x-dev"
         - PHPUNIT_TEST=1
         - PHPCS_TEST=1
-    - php: 7.3
+    - php: 7.4
       env:
         - DB=MYSQL
-        - REQUIRE_INSTALLER="4.7.x-dev"
-        - BEHAT_TEST=1
-        - BEHAT_SUITE="userforms"
+        - REQUIRE_INSTALLER="4.x-dev"
+        - PHPUNIT_COVERAGE_TEST=1
     - php: 7.4
       env:
         - DB=MYSQL
         - REQUIRE_INSTALLER="4.x-dev"
-        - PHPUNIT_COVERAGE_TEST=1
-    - php: nightly
+        - BEHAT_TEST=1
+        - BEHAT_SUITE="userforms"
+    - php: 8.0
       env:
         - DB=MYSQL
         - REQUIRE_INSTALLER="4.x-dev"
diff --git a/composer.json b/composer.json
index 346e9b234..d5afa1971 100644
--- a/composer.json
+++ b/composer.json
@@ -30,7 +30,8 @@
         }
     ],
     "require": {
-        "php": ">=7.1",
+        "php": "^7.3 || ^8.0",
+        "silverstripe/framework": "^4.10",
         "silverstripe/cms": "^4.6",
         "symbiote/silverstripe-gridfieldextensions": "^3.1",
         "silverstripe/segment-field": "^2.0",
@@ -38,7 +39,7 @@
         "silverstripe/mimevalidator": "^2.0"
     },
     "require-dev": {
-        "sminnee/phpunit": "^5.7",
+        "phpunit/phpunit": "^9.5",
         "squizlabs/php_codesniffer": "^3.0"
     },
     "autoload": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 50a2f923e..777d77277 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,7 +1,9 @@
 <phpunit bootstrap="vendor/silverstripe/cms/tests/bootstrap.php" colors="true">
-    <testsuite name="Default">
-        <directory>tests/</directory>
-    </testsuite>
+    <testsuites>
+        <testsuite name="Default">
+            <directory>tests/</directory>
+        </testsuite>
+    </testsuites>
     <filter>
         <whitelist addUncoveredFilesFromWhitelist="true">
             <directory suffix=".php">code/</directory>
diff --git a/tests/Extension/UserFormFieldEditorExtensionTest.php b/tests/Extension/UserFormFieldEditorExtensionTest.php
index 18e29a3b0..067d6e4b6 100644
--- a/tests/Extension/UserFormFieldEditorExtensionTest.php
+++ b/tests/Extension/UserFormFieldEditorExtensionTest.php
@@ -15,7 +15,7 @@ class UserFormFieldEditorExtensionTest extends SapphireTest
         UserFormBlockStub::class,
     ];
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $page = $this->objFromFixture(UserDefinedForm::class, 'page');
diff --git a/tests/Model/Recipient/UserFormRecipientItemRequestTest.php b/tests/Model/Recipient/UserFormRecipientItemRequestTest.php
index 65b20b314..ef8e17382 100644
--- a/tests/Model/Recipient/UserFormRecipientItemRequestTest.php
+++ b/tests/Model/Recipient/UserFormRecipientItemRequestTest.php
@@ -38,10 +38,10 @@ public function testShowInReportsAffectsPreview()
         $request = new UserFormRecipientItemRequest(null, null, $recipient, null, '');
         $html = $request->preview()->getValue();
         foreach ($falseClasses as $class) {
-            $this->assertNotContains('My' . $class, $html);
+            $this->assertStringNotContainsString('My' . $class, $html);
         }
         foreach ($trueClasses as $class) {
-            $this->assertContains('My' . $class, $html);
+            $this->assertStringContainsString('My' . $class, $html);
         }
     }
 }
diff --git a/tests/php/Control/UserDefinedFormAdminTest.php b/tests/php/Control/UserDefinedFormAdminTest.php
index 0f054ea6a..1effe7520 100644
--- a/tests/php/Control/UserDefinedFormAdminTest.php
+++ b/tests/php/Control/UserDefinedFormAdminTest.php
@@ -38,7 +38,7 @@ class UserDefinedFormAdminTest extends FunctionalTest
 {
     protected static $fixture_file = '../UserFormsTest.yml';
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -401,7 +401,7 @@ public function testGetFolderPermissionValidRequest()
             $response->getStatusCode(),
             'Valid request is successfull'
         );
-        $this->assertContains('Unrestricted access, uploads will be visible to anyone', $response->getBody());
+        $this->assertStringContainsString('Unrestricted access, uploads will be visible to anyone', $response->getBody());
 
         $folder = Folder::find('restricted-folder');
         $response = $this->get($url . http_build_query(['FolderID' => 0]));
@@ -410,7 +410,7 @@ public function testGetFolderPermissionValidRequest()
             $response->getStatusCode(),
             'Valid request for root folder is successful'
         );
-        $this->assertContains('Unrestricted access, uploads will be visible to anyone', $response->getBody());
+        $this->assertStringContainsString('Unrestricted access, uploads will be visible to anyone', $response->getBody());
 
         $folder = Folder::find('restricted-folder');
         $response = $this->get($url . http_build_query(['FolderID' => $folder->ID]));
@@ -419,7 +419,7 @@ public function testGetFolderPermissionValidRequest()
             $response->getStatusCode(),
             'Valid request for root folder is successful'
         );
-        $this->assertContains('Restricted access, uploads will be visible to logged-in users ', $response->getBody());
+        $this->assertStringContainsString('Restricted access, uploads will be visible to logged-in users ', $response->getBody());
 
         $this->logInWithPermission('ADMIN');
         $adminOnlyFolder = Folder::find('admin-only');
@@ -429,7 +429,7 @@ public function testGetFolderPermissionValidRequest()
             $response->getStatusCode(),
             'Valid request for folder restricted to group is successful'
         );
-        $this->assertContains('Restricted access, uploads will be visible to the following groups: Administrators', $response->getBody());
+        $this->assertStringContainsString('Restricted access, uploads will be visible to the following groups: Administrators', $response->getBody());
     }
 
     public function testGetFormSubmissionFolder()
diff --git a/tests/php/Control/UserDefinedFormControllerTest.php b/tests/php/Control/UserDefinedFormControllerTest.php
index b907027f9..a198f4134 100644
--- a/tests/php/Control/UserDefinedFormControllerTest.php
+++ b/tests/php/Control/UserDefinedFormControllerTest.php
@@ -39,7 +39,7 @@ class UserDefinedFormControllerTest extends FunctionalTest
 
     protected static $disable_themes = true;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -49,7 +49,7 @@ protected function setUp()
         Config::modify()->merge(SSViewer::class, 'themes', ['simple', '$default']);
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -105,11 +105,11 @@ public function testProcess()
         $this->assertEmailSent('nohtml@example.com', 'no-reply@example.com', 'Email Subject');
         $nohtml = $this->findEmail('nohtml@example.com', 'no-reply@example.com', 'Email Subject');
 
-        $this->assertContains('Basic Text Field: Basic Value', $nohtml['Content'], 'Email contains no html');
+        $this->assertStringContainsString('Basic Text Field: Basic Value', $nohtml['Content'], 'Email contains no html');
 
         // submitted html tags are not escaped because the email is being sent as text/plain
         $value = 'My body text Basic Value <b>HTML</b>';
-        $this->assertContains($value, $nohtml['Content'], 'Email contains the merge field value');
+        $this->assertStringContainsString($value, $nohtml['Content'], 'Email contains the merge field value');
 
         // no data
         $this->assertEmailSent('nodata@example.com', 'no-reply@example.com', 'Email Subject');
@@ -123,7 +123,7 @@ public function testProcess()
         // check to see if the user was redirected (301)
         $this->assertEquals($response->getStatusCode(), 302);
         $location = $response->getHeader('Location');
-        $this->assertContains('finished', $location);
+        $this->assertStringContainsString('finished', $location);
         $this->assertStringEndsWith('#uff', $location);
 
         // check that multiple email addresses are supported in to and from
@@ -142,7 +142,7 @@ public function testValidation()
         $this->get($form->URLSegment);
         /** @var HTTPResponse $response */
         $response = $this->submitForm('UserForm_Form_' . $form->ID, null, []);
-        $this->assertContains('This field is required', $response->getBody());
+        $this->assertStringContainsString('This field is required', $response->getBody());
 
         // Post with all fields, but invalid email
         $this->get($form->URLSegment);
@@ -151,7 +151,7 @@ public function testValidation()
             'required-email' => 'invalid',
             'required-text' => 'bob'
         ]);
-        $this->assertContains('Please enter an email address', $response->getBody());
+        $this->assertStringContainsString('Please enter an email address', $response->getBody());
 
         // Post with only required
         $this->get($form->URLSegment);
@@ -159,7 +159,7 @@ public function testValidation()
         $response = $this->submitForm('UserForm_Form_' . $form->ID, null, [
             'required-text' => 'bob'
         ]);
-        $this->assertContains("Thanks, we've received your submission.", $response->getBody());
+        $this->assertStringContainsString("Thanks, we've received your submission.", $response->getBody());
     }
 
     public function testFinished()
@@ -172,7 +172,7 @@ public function testFinished()
 
         $response = $this->get($form->URLSegment.'/finished');
 
-        $this->assertContains($form->OnCompleteMessage, $response->getBody());
+        $this->assertStringContainsString($form->OnCompleteMessage, $response->getBody());
     }
 
     public function testAppendingFinished()
@@ -185,7 +185,7 @@ public function testAppendingFinished()
 
         $response = $this->get($form->URLSegment.'/finished');
 
-        $this->assertNotContains($form->OnCompleteMessage, $response->getBody());
+        $this->assertStringNotContainsString($form->OnCompleteMessage, $response->getBody());
     }
 
     public function testForm()
@@ -320,7 +320,7 @@ public function testRenderingIntoTemplateWithDisabledInterpolation()
         $parser = new CSSContentParser($html);
 
         // Assert Content has been rendered with the shortcode in place
-        $this->assertContains('<p>Here is my form</p><p>$UserDefinedForm</p><p>Thank you for filling it out</p>', $html);
+        $this->assertStringContainsString('<p>Here is my form</p><p>$UserDefinedForm</p><p>Thank you for filling it out</p>', $html);
         // And the form in the $From area
         $this->assertArrayHasKey(0, $parser->getBySelector('form#UserForm_Form_' . $form->ID));
         // check for the input
diff --git a/tests/php/Model/EditableCustomRuleTest.php b/tests/php/Model/EditableCustomRuleTest.php
index c87b9490c..e717cd39e 100644
--- a/tests/php/Model/EditableCustomRuleTest.php
+++ b/tests/php/Model/EditableCustomRuleTest.php
@@ -23,7 +23,7 @@ public function testBuildExpression()
         $this->assertNotEmpty($result1['operation']);
 
         //Check for equals sign
-        $this->assertContains('==', $result1['operation']);
+        $this->assertStringContainsString('==', $result1['operation']);
 
         /** @var EditableCustomRule $rule2 */
         $rule2 = $this->objFromFixture(EditableCustomRule::class, 'rule2');
@@ -34,7 +34,7 @@ public function testBuildExpression()
         $this->assertNotEmpty($result2['operation']);
 
         //Check for greater than sign
-        $this->assertContains('>', $result2['operation']);
+        $this->assertStringContainsString('>', $result2['operation']);
     }
 
     /**
@@ -133,11 +133,9 @@ public function testValidateAgainstFormData($condition, $targetValue, $value, $e
         );
     }
 
-    /**
-     * @expectedException LogicException
-     */
     public function testValidateAgainstFormDataWithNonSenseRule()
     {
+        $this->expectException(\LogicException::class);
         $rule1 = $this->objFromFixture(EditableCustomRule::class, 'rule1');
         $rule1->ConditionOption = 'NonSenseRule';
         $rule1->validateAgainstFormData(['CountrySelection' => 'booya']);
diff --git a/tests/php/Model/EditableFormField/EditableCountryDropdownFieldTest.php b/tests/php/Model/EditableFormField/EditableCountryDropdownFieldTest.php
index 4bbd0196e..4426ead80 100644
--- a/tests/php/Model/EditableFormField/EditableCountryDropdownFieldTest.php
+++ b/tests/php/Model/EditableFormField/EditableCountryDropdownFieldTest.php
@@ -12,7 +12,7 @@ public function testGetIcon()
     {
         $field = new EditableCountryDropdownField;
 
-        $this->assertContains('/images/editabledropdown.png', $field->getIcon());
+        $this->assertStringContainsString('/images/editabledropdown.png', $field->getIcon());
     }
 
     public function testAllowEmptyTitle()
diff --git a/tests/php/Model/EditableFormField/EditableFileFieldTest.php b/tests/php/Model/EditableFormField/EditableFileFieldTest.php
index 72b21b0eb..1b659ac0e 100644
--- a/tests/php/Model/EditableFormField/EditableFileFieldTest.php
+++ b/tests/php/Model/EditableFormField/EditableFileFieldTest.php
@@ -22,7 +22,7 @@ class EditableFileFieldTest extends SapphireTest
     /**
      * Hold the server default max file size upload limit for later
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -48,7 +48,7 @@ public function testValidateFileSizeFieldValue()
     {
 
         $fileField = $this->objFromFixture(EditableFileField::class, 'file-field');
-        $this->setExpectedException(ValidationException::class);
+        $this->expectException(ValidationException::class);
         $fileField->MaxFileSizeMB = $this->php_max_file_size * 2;
         $fileField->write();
     }
diff --git a/tests/php/Model/EditableFormField/EditableLiteralFieldTest.php b/tests/php/Model/EditableFormField/EditableLiteralFieldTest.php
index c12f77fa7..fa2753031 100644
--- a/tests/php/Model/EditableFormField/EditableLiteralFieldTest.php
+++ b/tests/php/Model/EditableFormField/EditableLiteralFieldTest.php
@@ -15,7 +15,7 @@
  */
 class EditableLiteralFieldTest extends SapphireTest
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $cmsConfig = HTMLEditorConfig::get('cms');
@@ -48,11 +48,11 @@ public function testHideLabel()
             'Title' => 'Test label'
         ]);
 
-        $this->assertContains('Test label', $field->getFormField()->FieldHolder());
+        $this->assertStringContainsString('Test label', $field->getFormField()->FieldHolder());
         $this->assertEquals('Test label', $field->getFormField()->Title());
 
         $field->HideLabel = true;
-        $this->assertNotContains('Test label', $field->getFormField()->FieldHolder());
+        $this->assertStringNotContainsString('Test label', $field->getFormField()->FieldHolder());
         $this->assertEmpty($field->getFormField()->Title());
     }
 
diff --git a/tests/php/Model/EditableFormField/EditableNumericFieldTest.php b/tests/php/Model/EditableFormField/EditableNumericFieldTest.php
index 035649ccb..afcd0add6 100644
--- a/tests/php/Model/EditableFormField/EditableNumericFieldTest.php
+++ b/tests/php/Model/EditableFormField/EditableNumericFieldTest.php
@@ -24,7 +24,7 @@ public function testValidateAddsErrorWhenMinValueIsGreaterThanMaxValue()
 
         $result = $field->validate();
         $this->assertFalse($result->isValid(), 'Validation should fail when min is greater than max');
-        $this->assertContains('Minimum length should be less than the maximum length', $result->serialize());
+        $this->assertStringContainsString('Minimum length should be less than the maximum length', $result->serialize());
     }
 
     public function testValidate()
diff --git a/tests/php/Model/EditableFormFieldTest.php b/tests/php/Model/EditableFormFieldTest.php
index 3058c8692..7bda25013 100644
--- a/tests/php/Model/EditableFormFieldTest.php
+++ b/tests/php/Model/EditableFormFieldTest.php
@@ -184,9 +184,9 @@ public function testUniqueName()
         $checkboxField->write();
 
         // Test values are in the expected format
-        $this->assertRegExp('/^EditableTextField_.+/', $textfield1->Name);
-        $this->assertRegExp('/^EditableTextField_.+/', $textfield2->Name);
-        $this->assertRegExp('/^EditableCheckbox_.+/', $checkboxField->Name);
+        $this->assertMatchesRegularExpression('/^EditableTextField_.+/', $textfield1->Name);
+        $this->assertMatchesRegularExpression('/^EditableTextField_.+/', $textfield2->Name);
+        $this->assertMatchesRegularExpression('/^EditableCheckbox_.+/', $checkboxField->Name);
         $this->assertNotEquals($textfield1->Name, $textfield2->Name);
     }
 
@@ -238,7 +238,7 @@ public function testGetIcon()
     {
         $field = new EditableTextField;
 
-        $this->assertContains('/images/editabletextfield.png', $field->getIcon());
+        $this->assertStringContainsString('/images/editabletextfield.png', $field->getIcon());
     }
 
     public function displayedProvider()
diff --git a/tests/php/Model/Recipient/EmailRecipientTest.php b/tests/php/Model/Recipient/EmailRecipientTest.php
index 0de6ae8e6..481d0ccc2 100644
--- a/tests/php/Model/Recipient/EmailRecipientTest.php
+++ b/tests/php/Model/Recipient/EmailRecipientTest.php
@@ -20,21 +20,19 @@ public function testShortcodesAreRenderedInEmailPreviewContent()
         $recipient->EmailBodyHtml = '<p>Some email content. About us: [sitetree_link,id=' . $page->ID . '].</p>';
 
         $result = $recipient->getEmailBodyContent();
-        $this->assertContains('/about-us/', $result);
+        $this->assertStringContainsString('/about-us/', $result);
 
         $recipient->SendPlain = true;
         $recipient->EmailBody = 'Some email content. About us: [sitetree_link,id=' . $page->ID . '].';
 
         $result = $recipient->getEmailBodyContent();
-        $this->assertContains('/about-us/', $result);
+        $this->assertStringContainsString('/about-us/', $result);
     }
 
-    /**
-     * @expectedException \SilverStripe\ORM\ValidationException
-     * @expectedExceptionMessage "Send email to" address or field is required
-     */
     public function testEmptyRecipientFailsValidation()
     {
+        $this->expectException(\SilverStripe\ORM\ValidationException::class);
+        $this->expectExceptionMessage('"Send email to" address or field is required');
         $recipient = new EmailRecipient();
         $recipient->EmailFrom = 'test@example.com';
         $recipient->write();
diff --git a/tests/php/Model/SubmittedFileFieldTest.php b/tests/php/Model/SubmittedFileFieldTest.php
index 91db2f933..397dcc046 100644
--- a/tests/php/Model/SubmittedFileFieldTest.php
+++ b/tests/php/Model/SubmittedFileFieldTest.php
@@ -11,14 +11,14 @@
 
 class SubmittedFileFieldTest extends SapphireTest
 {
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
         TestAssetStore::activate('SubmittedFileFieldTest');
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
 
@@ -40,7 +40,7 @@ public function testDeletingSubmissionRemovesFile()
         $submittedFile->ParentID = $submittedForm->ID;
         $submittedFile->write();
 
-        $this->assertContains('test-SubmittedFileFieldTest', $submittedFile->getFileName(), 'Submitted file is linked');
+        $this->assertStringContainsString('test-SubmittedFileFieldTest', $submittedFile->getFileName(), 'Submitted file is linked');
 
         $submittedForm->delete();
         $fileId = $file->ID;
diff --git a/tests/php/Model/UserDefinedFormTest.php b/tests/php/Model/UserDefinedFormTest.php
index 1c0e7b9c6..6f040f487 100644
--- a/tests/php/Model/UserDefinedFormTest.php
+++ b/tests/php/Model/UserDefinedFormTest.php
@@ -37,7 +37,7 @@ class UserDefinedFormTest extends FunctionalTest
         UserDefinedForm::class => [UserFormFieldEditorExtension::class],
     ];
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         Email::config()->update('admin_email', 'no-reply@example.com');
@@ -526,12 +526,12 @@ public function testIndex()
         $result = $this->get($page->Link());
         $body = Convert::nl2os($result->getBody(), ''); // strip out newlines
         $this->assertFalse($result->isError());
-        $this->assertContains('<p>Here is my form</p><form', $body);
-        $this->assertContains('</form><p>Thank you for filling it out</p>', $body);
+        $this->assertStringContainsString('<p>Here is my form</p><form', $body);
+        $this->assertStringContainsString('</form><p>Thank you for filling it out</p>', $body);
 
-        $this->assertNotContains('<p>$UserDefinedForm</p>', $body);
-        $this->assertNotContains('<p></p>', $body);
-        $this->assertNotContains('</p><p>Thank you for filling it out</p>', $body);
+        $this->assertStringNotContainsString('<p>$UserDefinedForm</p>', $body);
+        $this->assertStringNotContainsString('<p></p>', $body);
+        $this->assertStringNotContainsString('</p><p>Thank you for filling it out</p>', $body);
     }
 
     public function testEmailAddressValidation()
@@ -546,8 +546,8 @@ public function testEmailAddressValidation()
         $result = $recipient->validate();
         $this->assertFalse($result->isValid());
         $this->assertNotEmpty($result->getMessages());
-        $this->assertContains('filtered.example.com', $result->getMessages()[0]['message']);
-        $this->assertNotContains('filtered2@example.com', $result->getMessages()[0]['message']);
+        $this->assertStringContainsString('filtered.example.com', $result->getMessages()[0]['message']);
+        $this->assertStringNotContainsString('filtered2@example.com', $result->getMessages()[0]['message']);
 
         // test valid email addresses pass validation
         $recipient = $this->objFromFixture(