diff --git a/moodle/Tests/MoodleStandardTest.php b/moodle/Tests/MoodleStandardTest.php
index 046178c..b4bcaf6 100644
--- a/moodle/Tests/MoodleStandardTest.php
+++ b/moodle/Tests/MoodleStandardTest.php
@@ -32,6 +32,63 @@
  */
 class MoodleStandardTest extends MoodleCSBaseTestCase {
 
+    /**
+     * Test the PSR12.Functions.ReturnTypeDeclaration sniff.
+     *
+     * @covers \PHP_CodeSniffer\Standards\PSR12\Sniffs\Functions\ReturnTypeDeclarationSniff
+     */
+    public function test_psr12_functions_returntypedeclaration() {
+
+        // Define the standard, sniff and fixture to use.
+        $this->set_standard('moodle');
+        $this->set_sniff('PSR12.Functions.ReturnTypeDeclaration');
+        $this->set_fixture(__DIR__ . '/fixtures/psr12_functions_returntypedeclaration.php');
+
+        // Define expected results (errors and warnings). Format, array of:
+        // - line => number of problems,  or
+        // - line => array of contents for message / source problem matching.
+        // - line => string of contents for message / source problem matching (only 1).
+        $errors = [
+            30 => 'SpaceBeforeColon',
+            34 => 'SpaceBeforeReturnType',
+            38 => 'SpaceBeforeReturnType',
+        ];
+        $warnings = [];
+        $this->set_errors($errors);
+        $this->set_warnings($warnings);
+
+        // Let's do all the hard work!
+        $this->verify_cs_results();
+    }
+
+    /**
+     * Test the PSR12.Functions.NullableTypeDeclaration sniff.
+     *
+     * @covers \PHP_CodeSniffer\Standards\PSR12\Sniffs\Functions\NullableTypeDeclarationSniff
+     */
+    public function test_psr12_functions_nullabletypedeclaration() {
+
+        // Define the standard, sniff and fixture to use.
+        $this->set_standard('moodle');
+        $this->set_sniff('PSR12.Functions.NullableTypeDeclaration');
+        $this->set_fixture(__DIR__ . '/fixtures/psr12_functions_nullabletypedeclaration.php');
+
+        // Define expected results (errors and warnings). Format, array of:
+        // - line => number of problems,  or
+        // - line => array of contents for message / source problem matching.
+        // - line => string of contents for message / source problem matching (only 1).
+        $errors = [
+            17 => 'WhitespaceFound',
+            22 => 3,
+        ];
+        $warnings = [];
+        $this->set_errors($errors);
+        $this->set_warnings($warnings);
+
+        // Let's do all the hard work!
+        $this->verify_cs_results();
+    }
+
     /**
      * Test the PSR2.Methods.MethodDeclaration sniff.
      *
diff --git a/moodle/Tests/Sniffs/Methods/MethodDeclarationSpacingSniffTest.php b/moodle/Tests/Sniffs/Methods/MethodDeclarationSpacingSniffTest.php
new file mode 100644
index 0000000..365cd10
--- /dev/null
+++ b/moodle/Tests/Sniffs/Methods/MethodDeclarationSpacingSniffTest.php
@@ -0,0 +1,66 @@
+<?php
+// This file is part of Moodle - https://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <https://www.gnu.org/licenses/>.
+
+namespace MoodleHQ\MoodleCS\moodle\Tests\Sniffs\Methods;
+
+use MoodleHQ\MoodleCS\moodle\Tests\MoodleCSBaseTestCase;
+
+// phpcs:disable moodle.NamingConventions
+
+/**
+ * Test the MethodDeclarationSpacing sniff.
+ *
+ * @copyright  2024 onwards Eloy Lafuente (stronk7) {@link https://stronk7.com}
+ * @license    https://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ *
+ * @covers \MoodleHQ\MoodleCS\moodle\Sniffs\Methods\MethodDeclarationSpacingSniff
+ */
+class MethodDeclarationSpacingSniffTest extends MoodleCSBaseTestCase
+{
+    public function testMethodDeclarationSpacing(): void {
+        // Define the standard, sniff and fixture to use.
+        $this->set_standard('moodle');
+        $this->set_sniff('moodle.Methods.MethodDeclarationSpacing');
+        $this->set_fixture(__DIR__ . '/../../fixtures/Methods/MethodDeclarationSpacing.php');
+
+        // Define expected results (errors and warnings). Format, array of:
+        // - line => number of problems,  or
+        // - line => array of contents for message / source problem matching.
+        // - line => string of contents for message / source problem matching (only 1).
+        $errors = [
+            43 => 4,
+            45 => [
+                'Expected 0 spaces after "("; 2 found',
+                'Expected 0 spaces after "method2"; 2 found',
+                'Expected 1 space after "function"; 2 found',
+                'Expected 1 space after "final"; 2 found',
+            ],
+            49 => [
+                'ZeroExpectedAfter',
+                'ZeroExpectedAfter',
+                'OneExpectedAfter',
+            ],
+            53 => 1,
+            61 => 3,
+        ];
+        $warnings = [];
+        $this->set_errors($errors);
+        $this->set_warnings($warnings);
+
+        // Let's do all the hard work!
+        $this->verify_cs_results();
+    }
+}
diff --git a/moodle/Tests/fixtures/Methods/MethodDeclarationSpacing.php b/moodle/Tests/fixtures/Methods/MethodDeclarationSpacing.php
new file mode 100644
index 0000000..b3d3dfb
--- /dev/null
+++ b/moodle/Tests/fixtures/Methods/MethodDeclarationSpacing.php
@@ -0,0 +1,64 @@
+<?php
+defined('MOODLE_INTERNAL') || die(); // Make this always the 1st line in all CS fixtures.
+
+// All the methods in this class are correct.
+class correct_methods {
+    abstract public static function method1();
+
+    final public static function method2() {
+        return true;
+    }
+
+    public function method3() {
+        return true;
+    }
+
+    public /* comment */ function method4() {
+        // We don't do anything with with closures.
+        $a = function () {
+            return true;
+        };
+        return true;
+    }
+}
+
+class nested_function_correct {
+    public function getAnonymousClass() {
+        return new class() {
+            public function nested_function() {}
+        };
+    }
+}
+
+// We don't do anything with with global scope functions.
+function   global_function  (  ) {
+    return true;
+}
+
+// All the methods in this class are incorrect.
+// (note that the MethodDeclarationSpacing DOES NOT fix all the
+// keywords in this class, because some are handled by other sniffs.
+// Take a look to the class documentation for more information).
+class incorrect_methods {
+    abstract  public  static  function  method3  (  );
+
+    final  public  static  function  method2  (  ) {
+        return  true;
+    }
+
+    public  function  method3  (  ) {
+        return  true;
+    }
+
+    public function method4 chocolate() {
+        return true;
+    }
+}
+
+class nested_function_incorrect {
+    public function getAnonymousClass() {
+        return new class() {
+            public function  nested_function  (  ) {}
+        };
+    }
+}
diff --git a/moodle/Tests/fixtures/Methods/MethodDeclarationSpacing.php.fixed b/moodle/Tests/fixtures/Methods/MethodDeclarationSpacing.php.fixed
new file mode 100644
index 0000000..cadd6c9
--- /dev/null
+++ b/moodle/Tests/fixtures/Methods/MethodDeclarationSpacing.php.fixed
@@ -0,0 +1,64 @@
+<?php
+defined('MOODLE_INTERNAL') || die(); // Make this always the 1st line in all CS fixtures.
+
+// All the methods in this class are correct.
+class correct_methods {
+    abstract public static function method1();
+
+    final public static function method2() {
+        return true;
+    }
+
+    public function method3() {
+        return true;
+    }
+
+    public /* comment */ function method4() {
+        // We don't do anything with with closures.
+        $a = function () {
+            return true;
+        };
+        return true;
+    }
+}
+
+class nested_function_correct {
+    public function getAnonymousClass() {
+        return new class() {
+            public function nested_function() {}
+        };
+    }
+}
+
+// We don't do anything with with global scope functions.
+function   global_function  (  ) {
+    return true;
+}
+
+// All the methods in this class are incorrect.
+// (note that the MethodDeclarationSpacing DOES NOT fix all the
+// keywords in this class, because some are handled by other sniffs.
+// Take a look to the class documentation for more information).
+class incorrect_methods {
+    abstract public  static  function method3();
+
+    final public  static  function method2() {
+        return  true;
+    }
+
+    public  function method3() {
+        return  true;
+    }
+
+    public function method4chocolate() {
+        return true;
+    }
+}
+
+class nested_function_incorrect {
+    public function getAnonymousClass() {
+        return new class() {
+            public function nested_function() {}
+        };
+    }
+}
diff --git a/moodle/Tests/fixtures/psr12_functions_nullabletypedeclaration.php b/moodle/Tests/fixtures/psr12_functions_nullabletypedeclaration.php
new file mode 100644
index 0000000..f1350ad
--- /dev/null
+++ b/moodle/Tests/fixtures/psr12_functions_nullabletypedeclaration.php
@@ -0,0 +1,24 @@
+<?php
+defined('MOODLE_INTERNAL') || die(); // Make this always the 1st line in all CS fixtures.
+
+// All the return types in this class are correct.
+class correct_methods {
+    public function return_type_nullable_ok(): ?int {
+        return 1;
+    }
+}
+
+function return_type_nullable_ok(): ?int {
+    return 1;
+}
+
+// All the return types in this class have problems..
+class incorrect_methods {
+    public function return_type_nullable_wrong(): ? int {
+        return 1;
+    }
+}
+
+function all_type_nullable_wrong(? int $one, ? int $two): ? int {
+    return 1;
+}
diff --git a/moodle/Tests/fixtures/psr12_functions_nullabletypedeclaration.php.fixed b/moodle/Tests/fixtures/psr12_functions_nullabletypedeclaration.php.fixed
new file mode 100644
index 0000000..9b4a8f3
--- /dev/null
+++ b/moodle/Tests/fixtures/psr12_functions_nullabletypedeclaration.php.fixed
@@ -0,0 +1,24 @@
+<?php
+defined('MOODLE_INTERNAL') || die(); // Make this always the 1st line in all CS fixtures.
+
+// All the return types in this class are correct.
+class correct_methods {
+    public function return_type_nullable_ok(): ?int {
+        return 1;
+    }
+}
+
+function return_type_nullable_ok(): ?int {
+    return 1;
+}
+
+// All the return types in this class have problems..
+class incorrect_methods {
+    public function return_type_nullable_wrong(): ?int {
+        return 1;
+    }
+}
+
+function all_type_nullable_wrong(?int $one, ?int $two): ?int {
+    return 1;
+}
diff --git a/moodle/Tests/fixtures/psr12_functions_returntypedeclaration.php b/moodle/Tests/fixtures/psr12_functions_returntypedeclaration.php
new file mode 100644
index 0000000..2eee8f5
--- /dev/null
+++ b/moodle/Tests/fixtures/psr12_functions_returntypedeclaration.php
@@ -0,0 +1,46 @@
+<?php
+defined('MOODLE_INTERNAL') || die(); // Make this always the 1st line in all CS fixtures.
+
+// All the return types in this class are correct.
+class correct_methods {
+    public function no_return_type() {
+        return;
+    }
+
+    public function return_void(): void {
+        return null;
+    }
+
+    public function return_type(): int {
+        return 1;
+    }
+
+    public function return_type_nullable(): ?int {
+        return 1;
+    }
+
+    public function return_type_union(): int|string|null {
+        return null;
+    }
+}
+
+// All the return types in this class have problems..
+class incorrect_methods {
+
+    public function return_wrong_colon_many_spacing()   : int {
+        return 1;
+    }
+
+    public function return_wrong_type_many_spacing():   int {
+        return 1;
+    }
+
+    public function return_wrong_type_no_spacing():int {
+        return 1;
+    }
+
+    // Note this corresponds to the PSR12.Functions.NullableTypeDeclaration Sniff, so it's correct for this fixture.
+    public function return_wrong_nullable_many_spacing(): ?   int {
+        return 1;
+    }
+}
diff --git a/moodle/Tests/fixtures/psr12_functions_returntypedeclaration.php.fixed b/moodle/Tests/fixtures/psr12_functions_returntypedeclaration.php.fixed
new file mode 100644
index 0000000..dd73c06
--- /dev/null
+++ b/moodle/Tests/fixtures/psr12_functions_returntypedeclaration.php.fixed
@@ -0,0 +1,46 @@
+<?php
+defined('MOODLE_INTERNAL') || die(); // Make this always the 1st line in all CS fixtures.
+
+// All the return types in this class are correct.
+class correct_methods {
+    public function no_return_type() {
+        return;
+    }
+
+    public function return_void(): void {
+        return null;
+    }
+
+    public function return_type(): int {
+        return 1;
+    }
+
+    public function return_type_nullable(): ?int {
+        return 1;
+    }
+
+    public function return_type_union(): int|string|null {
+        return null;
+    }
+}
+
+// All the return types in this class have problems..
+class incorrect_methods {
+
+    public function return_wrong_colon_many_spacing(): int {
+        return 1;
+    }
+
+    public function return_wrong_type_many_spacing(): int {
+        return 1;
+    }
+
+    public function return_wrong_type_no_spacing(): int {
+        return 1;
+    }
+
+    // Note this corresponds to the PSR12.Functions.NullableTypeDeclaration Sniff, so it's correct for this fixture.
+    public function return_wrong_nullable_many_spacing(): ?   int {
+        return 1;
+    }
+}