diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 27b1aa42ba..8dd294c50c 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -346,6 +346,36 @@ However, there are a few places which include OS-specific conditions, most notab
 
 Tests which cover code which have Windows specific conditions should be marked with a `@group Windows` annotation to allow for running those tests separately/selectively in CI.
 
+#### Tests covering code which has CS/CBF specific behaviour
+
+There are a few places in PHPCS where code uses a global `PHP_CODESNIFFER_CBF` constant to determine what to do.
+This makes testing this code more complicated.
+
+Tests which will only work correctly when `PHP_CODESNIFFER_CBF === false` should get the following test skip condition at the top of the test method:
+```php
+if (PHP_CODESNIFFER_CBF === true) {
+    $this->markTestSkipped('This test needs CS mode to run');
+}
+```
+
+Tests which are specifically intended to cover code run when `PHP_CODESNIFFER_CBF === true` should:
+1. Be annotated with `@group CBF`.
+2. Have a test skip condition at the top of the test method like so:
+    ```php
+    if (PHP_CODESNIFFER_CBF === false) {
+        $this->markTestSkipped('This test needs CBF mode to run');
+    }
+    ```
+
+By default, the tests are run with the `PHP_CODESNIFFER_CBF` constant set to `false` and tests in the `@group CBF` will not be run.
+
+To run the tests specific to the use of `PHP_CODESNIFFER_CBF === true`:
+1. Set `<php><env name="PHP_CODESNIFFER_CBF" value="1"/></php>` in a `phpunit.xml` file or set the ENV variable on an OS-level.
+2. Run the tests like so:
+    ```bash
+    vendor/bin/phpunit --group CBF --exclude-group nothing
+    ```
+
 
 ### Submitting Your Pull Request
 
diff --git a/.github/workflows/quicktest.yml b/.github/workflows/quicktest.yml
index ed24bec539..5edde2a41a 100644
--- a/.github/workflows/quicktest.yml
+++ b/.github/workflows/quicktest.yml
@@ -76,6 +76,11 @@ jobs:
         if: ${{ matrix.os == 'windows-latest' }}
         run: php "vendor/bin/phpunit" tests/AllTests.php --group Windows --no-coverage
 
+      - name: 'PHPUnit: run select tests in CBF mode'
+        run: php "vendor/bin/phpunit" tests/AllTests.php --group CBF --exclude-group nothing --no-coverage
+        env:
+          PHP_CODESNIFFER_CBF: '1'
+
       # Note: The code style check is run as an integration test.
       - name: 'PHPCS: check code style without cache, no parallel'
         run: php "bin/phpcs" --no-cache --parallel=1
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 0113b7e8a7..e84fad9571 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -183,6 +183,11 @@ jobs:
         if: ${{ matrix.skip_tests != true }}
         run: php "vendor/bin/phpunit" tests/AllTests.php --no-coverage
 
+      - name: 'PHPUnit: run select tests in CBF mode'
+        run: php "vendor/bin/phpunit" tests/AllTests.php --group CBF --exclude-group nothing --no-coverage
+        env:
+          PHP_CODESNIFFER_CBF: '1'
+
       - name: 'PHPCS: check code style without cache, no parallel'
         if: ${{ matrix.custom_ini == false && matrix.php != '7.4' }}
         run: php "bin/phpcs" --no-cache --parallel=1
@@ -311,6 +316,22 @@ jobs:
         if: ${{ matrix.os != 'windows-latest' && steps.phpunit_version.outputs.VERSION >= '9.3' }}
         run: php "vendor/bin/phpunit" tests/AllTests.php --coverage-cache ./build/phpunit-cache
 
+      - name: "Run select tests in CBF mode with code coverage (PHPUnit < 9.3)"
+        if: ${{ matrix.os != 'windows-latest' && steps.phpunit_version.outputs.VERSION < '9.3' }}
+        run: >
+          php "vendor/bin/phpunit" tests/AllTests.php
+          --group CBF --exclude-group nothing --coverage-clover build/logs/clover-cbf.xml
+        env:
+          PHP_CODESNIFFER_CBF: '1'
+
+      - name: "Run select tests in CBF mode with code coverage (PHPUnit 9.3+)"
+        if: ${{ matrix.os != 'windows-latest' && steps.phpunit_version.outputs.VERSION >= '9.3' }}
+        run: >
+          php "vendor/bin/phpunit" tests/AllTests.php --coverage-cache ./build/phpunit-cache
+          --group CBF --exclude-group nothing --coverage-clover build/logs/clover-cbf.xml
+        env:
+          PHP_CODESNIFFER_CBF: '1'
+
       - name: "Run the unit tests which may have different outcomes on Windows with code coverage (PHPUnit < 9.3)"
         if: ${{ matrix.os == 'windows-latest' && steps.phpunit_version.outputs.VERSION < '9.3' }}
         run: php "vendor/bin/phpunit" tests/AllTests.php --group Windows
@@ -319,7 +340,7 @@ jobs:
         if: ${{ matrix.os == 'windows-latest' && steps.phpunit_version.outputs.VERSION >= '9.3' }}
         run: php "vendor/bin/phpunit" tests/AllTests.php --group Windows --coverage-cache ./build/phpunit-cache
 
-      - name: Upload coverage results to Coveralls
+      - name: "Upload coverage results to Coveralls (normal run)"
         if: ${{ success() }}
         uses: coverallsapp/github-action@v2
         with:
@@ -328,6 +349,15 @@ jobs:
           flag-name: os-${{ matrix.os }}-php-${{ matrix.php }}-custom-ini-${{ matrix.custom_ini }}
           parallel: true
 
+      - name: "Upload coverage results to Coveralls (CBF run)"
+        if: ${{ matrix.os != 'windows-latest' && success() }}
+        uses: coverallsapp/github-action@v2
+        with:
+          format: clover
+          file: build/logs/clover-cbf.xml
+          flag-name: cbf-os-${{ matrix.os }}-ubuntu-latest-php-${{ matrix.php }}-custom-ini-${{ matrix.custom_ini }}
+          parallel: true
+
   coveralls-finish:
     needs: coverage
     if: always() && needs.coverage.result == 'success'
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 1402588f20..cf2b588c86 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -18,6 +18,12 @@
         </testsuite>
     </testsuites>
 
+    <groups>
+        <exclude>
+            <group>CBF</group>
+        </exclude>
+    </groups>
+
     <filter>
         <whitelist addUncoveredFilesFromWhitelist="true" processUncoveredFilesFromWhitelist="false">
             <directory suffix=".php">./src</directory>
@@ -32,4 +38,8 @@
         <log type="coverage-text" target="php://stdout" showOnlySummary="true"/>
         <log type="coverage-clover" target="build/logs/clover.xml"/>
     </logging>
+
+    <php>
+        <env name="PHP_CODESNIFFER_CBF" value="0"/>
+    </php>
 </phpunit>
diff --git a/tests/Core/Generators/GeneratorTest.php b/tests/Core/Generators/GeneratorTest.php
index 30536518f6..441c499874 100644
--- a/tests/Core/Generators/GeneratorTest.php
+++ b/tests/Core/Generators/GeneratorTest.php
@@ -201,6 +201,10 @@ public static function dataGeneratingDocs()
      */
     public function testGeneratorWillShowEachStandardSeparately()
     {
+        if (PHP_CODESNIFFER_CBF === true) {
+            $this->markTestSkipped('This test needs CS mode to run');
+        }
+
         $standard        = __DIR__.'/OneDocTest.xml';
         $_SERVER['argv'] = [
             'phpcs',
diff --git a/tests/Core/Ruleset/ExplainTest.php b/tests/Core/Ruleset/ExplainTest.php
index 48df24f473..4ec5b48317 100644
--- a/tests/Core/Ruleset/ExplainTest.php
+++ b/tests/Core/Ruleset/ExplainTest.php
@@ -217,6 +217,10 @@ public function testExplainWithDeprecatedSniffs()
      */
     public function testExplainWillExplainEachStandardSeparately()
     {
+        if (PHP_CODESNIFFER_CBF === true) {
+            $this->markTestSkipped('This test needs CS mode to run');
+        }
+
         $standard        = __DIR__.'/ExplainSingleSniffTest.xml';
         $_SERVER['argv'] = [
             'phpcs',
diff --git a/tests/Core/Ruleset/ShowSniffDeprecationsTest.php b/tests/Core/Ruleset/ShowSniffDeprecationsTest.php
index c31f7b4a83..2a36c34c65 100644
--- a/tests/Core/Ruleset/ShowSniffDeprecationsTest.php
+++ b/tests/Core/Ruleset/ShowSniffDeprecationsTest.php
@@ -67,7 +67,7 @@ public static function dataHasSniffDeprecations()
 
 
     /**
-     * Test that the listing with deprecated sniffs will not show when specific command-line options are being used.
+     * Test that the listing with deprecated sniffs will not show when specific command-line options are being used [1].
      *
      * @param string        $standard       The standard to use for the test.
      * @param array<string> $additionalArgs Optional. Additional arguments to pass.
@@ -102,24 +102,62 @@ public function testDeprecatedSniffsListDoesNotShow($standard, $additionalArgs=[
     public static function dataDeprecatedSniffsListDoesNotShow()
     {
         return [
-            'Standard not using deprecated sniffs: PSR1'                   => [
+            'Standard not using deprecated sniffs: PSR1'     => [
                 'standard' => 'PSR1',
             ],
-            'Standard using deprecated sniffs; explain mode'               => [
+            'Standard using deprecated sniffs; explain mode' => [
                 'standard'       => __DIR__.'/ShowSniffDeprecationsTest.xml',
                 'additionalArgs' => ['-e'],
             ],
-            'Standard using deprecated sniffs; quiet mode'                 => [
+            'Standard using deprecated sniffs; quiet mode'   => [
                 'standard'       => __DIR__.'/ShowSniffDeprecationsTest.xml',
                 'additionalArgs' => ['-q'],
             ],
+        ];
+
+    }//end dataDeprecatedSniffsListDoesNotShow()
+
+
+    /**
+     * Test that the listing with deprecated sniffs will not show when specific command-line options are being used [2].
+     *
+     * {@internal Separate test method for the same thing as this test will only work in CS mode.}
+     *
+     * @param string        $standard       The standard to use for the test.
+     * @param array<string> $additionalArgs Optional. Additional arguments to pass.
+     *
+     * @dataProvider dataDeprecatedSniffsListDoesNotShowNeedsCsMode
+     *
+     * @return void
+     */
+    public function testDeprecatedSniffsListDoesNotShowNeedsCsMode($standard, $additionalArgs=[])
+    {
+        if (PHP_CODESNIFFER_CBF === true) {
+            $this->markTestSkipped('This test needs CS mode to run');
+        }
+
+        $this->testDeprecatedSniffsListDoesNotShow($standard, $additionalArgs);
+
+    }//end testDeprecatedSniffsListDoesNotShowNeedsCsMode()
+
+
+    /**
+     * Data provider.
+     *
+     * @see testDeprecatedSniffsListDoesNotShowNeedsCsMode()
+     *
+     * @return array<string, array<string, string|array<string>>>
+     */
+    public static function dataDeprecatedSniffsListDoesNotShowNeedsCsMode()
+    {
+        return [
             'Standard using deprecated sniffs; documentation is requested' => [
                 'standard'       => __DIR__.'/ShowSniffDeprecationsTest.xml',
                 'additionalArgs' => ['--generator=text'],
             ],
         ];
 
-    }//end dataDeprecatedSniffsListDoesNotShow()
+    }//end dataDeprecatedSniffsListDoesNotShowNeedsCsMode()
 
 
     /**
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index cf4936daa8..e8ebdbbdd0 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -11,8 +11,27 @@
     define('PHP_CODESNIFFER_IN_TESTS', true);
 }
 
+/*
+ * Determine whether the test suite should be run in CBF mode.
+ *
+ * Use `<php><env name="PHP_CODESNIFFER_CBF" value="1"/></php>` in a `phpunit.xml` file
+ * or set the ENV variable at an OS-level to enable CBF mode.
+ *
+ * To run the CBF specific tests, use the following command:
+ * vendor/bin/phpunit --group CBF --exclude-group nothing
+ *
+ * If the ENV variable has not been set, or is set to "false", the tests will run in CS mode.
+ */
+
 if (defined('PHP_CODESNIFFER_CBF') === false) {
-    define('PHP_CODESNIFFER_CBF', false);
+    $cbfMode = getenv('PHP_CODESNIFFER_CBF');
+    if ($cbfMode === '1') {
+        define('PHP_CODESNIFFER_CBF', true);
+        echo 'Note: Tests are running in "CBF" mode'.PHP_EOL.PHP_EOL;
+    } else {
+        define('PHP_CODESNIFFER_CBF', false);
+        echo 'Note: Tests are running in "CS" mode'.PHP_EOL.PHP_EOL;
+    }
 }
 
 if (defined('PHP_CODESNIFFER_VERBOSITY') === false) {