diff --git a/tests/Core/Util/SuggestTypeTest.php b/tests/Core/Util/SuggestTypeTest.php
new file mode 100644
index 0000000000..b143e6bc16
--- /dev/null
+++ b/tests/Core/Util/SuggestTypeTest.php
@@ -0,0 +1,224 @@
+<?php
+/**
+ * Tests for the \PHP_CodeSniffer\Util\Sniffs\Comments::suggestType() method.
+ *
+ * @author    Juliette Reinders Folmer <phpcs_nospam@adviesenzo.nl>
+ * @copyright 2019 Juliette Reinders Folmer. All rights reserved.
+ * @license   https://github.com/squizlabs/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
+ */
+
+namespace PHP_CodeSniffer\Tests\Core\Util;
+
+use PHP_CodeSniffer\Util\Common;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests for the \PHP_CodeSniffer\Util\Sniffs\Comments::suggestType() method.
+ *
+ * @covers \PHP_CodeSniffer\Util\Common::suggestType
+ */
+class SuggestTypeTest extends TestCase
+{
+
+
+    /**
+     * Test passing an empty type to the suggestType() method.
+     *
+     * @return void
+     */
+    public function testSuggestTypeEmpty()
+    {
+        $this->assertSame('', Common::suggestType(''));
+
+    }//end testSuggestTypeEmpty()
+
+
+    /**
+     * Test passing one of the allowed types to the suggestType() method.
+     *
+     * @param string $varType The type.
+     *
+     * @dataProvider dataSuggestTypeAllowedType
+     *
+     * @return void
+     */
+    public function testSuggestTypeAllowedType($varType)
+    {
+        $result = Common::suggestType($varType);
+        $this->assertSame($varType, $result);
+
+    }//end testSuggestTypeAllowedType()
+
+
+    /**
+     * Data provider.
+     *
+     * @see testSuggestTypeAllowedType()
+     *
+     * @return array<string, array<string>>
+     */
+    public function dataSuggestTypeAllowedType()
+    {
+        $data = [];
+        foreach (Common::$allowedTypes as $type) {
+            $data['Type: '.$type] = [$type];
+        }
+
+        return $data;
+
+    }//end dataSuggestTypeAllowedType()
+
+
+    /**
+     * Test passing one of the allowed types in the wrong case to the suggestType() method.
+     *
+     * @param string $varType  The type found.
+     * @param string $expected Expected suggested type.
+     *
+     * @dataProvider dataSuggestTypeAllowedTypeWrongCase
+     *
+     * @return void
+     */
+    public function testSuggestTypeAllowedTypeWrongCase($varType, $expected)
+    {
+        $result = Common::suggestType($varType);
+        $this->assertSame($expected, $result);
+
+    }//end testSuggestTypeAllowedTypeWrongCase()
+
+
+    /**
+     * Data provider.
+     *
+     * @see testSuggestTypeAllowedTypeWrongCase()
+     *
+     * @return array<string, array<string, string>>
+     */
+    public function dataSuggestTypeAllowedTypeWrongCase()
+    {
+        $data = [];
+        foreach (Common::$allowedTypes as $type) {
+            $data['Mixed case: '.$type] = [
+                'varType'  => ucfirst($type),
+                'expected' => $type,
+            ];
+            $data['Uppercase: '.$type]  = [
+                'varType'  => strtoupper($type),
+                'expected' => $type,
+            ];
+        }
+
+        return $data;
+
+    }//end dataSuggestTypeAllowedTypeWrongCase()
+
+
+    /**
+     * Test the suggestType() method for all other cases.
+     *
+     * @param string $varType  The type found.
+     * @param string $expected Expected suggested type.
+     *
+     * @dataProvider dataSuggestTypeOther
+     *
+     * @return void
+     */
+    public function testSuggestTypeOther($varType, $expected)
+    {
+        $result = Common::suggestType($varType);
+        $this->assertSame($expected, $result);
+
+    }//end testSuggestTypeOther()
+
+
+    /**
+     * Data provider.
+     *
+     * @see testSuggestTypeOther()
+     *
+     * @return array<string, array<string, string>>
+     */
+    public function dataSuggestTypeOther()
+    {
+        return [
+            // Short forms.
+            'Short form type: bool, lowercase'                                => [
+                'varType'  => 'bool',
+                'expected' => 'boolean',
+            ],
+            'Short form type: bool, uppercase'                                => [
+                'varType'  => 'BOOL',
+                'expected' => 'boolean',
+            ],
+            'Short form type: double, lowercase'                              => [
+                'varType'  => 'double',
+                'expected' => 'float',
+            ],
+            'Short form type: real, mixed case'                               => [
+                'varType'  => 'Real',
+                'expected' => 'float',
+            ],
+            'Short form type: double, mixed case'                             => [
+                'varType'  => 'DoUbLe',
+                'expected' => 'float',
+            ],
+            'Short form type: int, lowercase'                                 => [
+                'varType'  => 'int',
+                'expected' => 'integer',
+            ],
+            'Short form type: int, uppercase'                                 => [
+                'varType'  => 'INT',
+                'expected' => 'integer',
+            ],
+
+            // Array types.
+            'Array type: mixed case keyword, empty parentheses'               => [
+                'varType'  => 'Array()',
+                'expected' => 'array',
+            ],
+            'Array type: short form type as value within the parentheses'     => [
+                'varType'  => 'array(real)',
+                'expected' => 'array(float)',
+            ],
+            'Array type: short form type as key within the parentheses'       => [
+                'varType'  => 'array(int => object)',
+                'expected' => 'array(integer => object)',
+            ],
+            'Array type: valid specification'                                 => [
+                'varType'  => 'array(integer => array(string => resource))',
+                'expected' => 'array(integer => array(string => resource))',
+            ],
+            'Array type: short form + uppercase types within the parentheses' => [
+                'varType'  => 'ARRAY(BOOL => DOUBLE)',
+                'expected' => 'array(boolean => float)',
+            ],
+            'Array type: no space around the arrow within the parentheses'    => [
+                'varType'  => 'array(string=>resource)',
+                'expected' => 'array(string => resource)',
+            ],
+
+            // Incomplete array type.
+            'Array type: incomplete specification'                            => [
+                'varType'  => 'array(int =>',
+                'expected' => 'array',
+            ],
+
+            // Custom types are returned unchanged.
+            'Unknown type: "<string> => <int>"'                               => [
+                'varType'  => '<string> => <int>',
+                'expected' => '<string> => <int>',
+            ],
+            'Unknown type: "string[]"'                                        => [
+                'varType'  => 'string[]',
+                'expected' => 'string[]',
+            ],
+            'Unknown type: "\DateTime"'                                       => [
+                'varType'  => '\DateTime',
+                'expected' => '\DateTime',
+            ],
+        ];
+
+    }//end dataSuggestTypeOther()
+
+
+}//end class