diff --git a/Universal/Docs/ControlStructures/DisallowLonelyIfStandard.xml b/Universal/Docs/ControlStructures/DisallowLonelyIfStandard.xml
new file mode 100644
index 00000000..4c72980e
--- /dev/null
+++ b/Universal/Docs/ControlStructures/DisallowLonelyIfStandard.xml
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<documentation title="Disallow Lonely If">
+    <standard>
+    <![CDATA[
+    Disallows `if` statements as the only statement in an `else` block.
+
+    If an `if` statement is the only statement in the `else` block, use `elseif` instead.
+    ]]>
+    </standard>
+    <code_comparison>
+        <code title="Valid: use of elseif or if followed by another statement.">
+        <![CDATA[
+if ($foo) {
+    // ...
+} <em>elseif ($bar)</em> {
+    // ...
+}
+
+if ($foo) {
+    // ...
+} else {
+    <em>if ($bar) {
+        // ...
+    }
+
+    doSomethingElse();
+    </em>
+}
+
+        ]]>
+        </code>
+        <code title="Invalid: lonely if in an else block.">
+        <![CDATA[
+if ($foo) {
+    // ...
+} else {
+    <em>if ($bar) {
+        // ...
+    } else {
+        // ...
+    }</em>
+}
+        ]]>
+        </code>
+    </code_comparison>
+</documentation>
diff --git a/Universal/Sniffs/ControlStructures/DisallowLonelyIfSniff.php b/Universal/Sniffs/ControlStructures/DisallowLonelyIfSniff.php
new file mode 100644
index 00000000..397a9e13
--- /dev/null
+++ b/Universal/Sniffs/ControlStructures/DisallowLonelyIfSniff.php
@@ -0,0 +1,346 @@
+<?php
+/**
+ * PHPCSExtra, a collection of sniffs and standards for use with PHP_CodeSniffer.
+ *
+ * @package   PHPCSExtra
+ * @copyright 2020 PHPCSExtra Contributors
+ * @license   https://opensource.org/licenses/LGPL-3.0 LGPL3
+ * @link      https://github.com/PHPCSStandards/PHPCSExtra
+ */
+
+namespace PHPCSExtra\Universal\Sniffs\ControlStructures;
+
+use PHP_CodeSniffer\Files\File;
+use PHP_CodeSniffer\Sniffs\Sniff;
+use PHP_CodeSniffer\Util\Tokens;
+use PHPCSUtils\Utils\ControlStructures;
+use PHPCSUtils\Utils\GetTokensAsString;
+
+/**
+ * Disallow `if` statements as the only statement in an `else` block.
+ *
+ * Note: This sniff will not fix the indentation of the "inner" code. It is strongly recommended to run
+ * this sniff together with the `Generic.WhiteSpace.ScopeIndent` sniff to get the correct indentation.
+ *
+ * Inspired by the {@link https://eslint.org/docs/rules/no-lonely-if ESLint "no lonely if"} rule
+ * in response to upstream {@link https://github.com/squizlabs/PHP_CodeSniffer/issues/3206 PHPCS issue 3206}.
+ *
+ * @since 1.0.0
+ */
+class DisallowLonelyIfSniff implements Sniff
+{
+
+    /**
+     * Returns an array of tokens this test wants to listen for.
+     *
+     * @since 1.0.0
+     *
+     * @return array
+     */
+    public function register()
+    {
+        return [
+            \T_ELSE,
+        ];
+    }
+
+    /**
+     * Processes this test, when one of its tokens is encountered.
+     *
+     * @since 1.0.0
+     *
+     * @param \PHP_CodeSniffer\Files\File $phpcsFile The file being scanned.
+     * @param int                         $stackPtr  The position of the current token
+     *                                               in the stack passed in $tokens.
+     *
+     * @return void
+     */
+    public function process(File $phpcsFile, $stackPtr)
+    {
+        $tokens = $phpcsFile->getTokens();
+
+        /*
+         * Deal with `else if`.
+         */
+        if (ControlStructures::isElseIf($phpcsFile, $stackPtr) === true) {
+            // Ignore, not our real target.
+            return;
+        }
+
+        if (isset($tokens[$stackPtr]['scope_opener'], $tokens[$stackPtr]['scope_closer']) === false) {
+            // Either an else without curly braces or a parse error. Ignore.
+            return;
+        }
+
+        $outerScopeOpener = $tokens[$stackPtr]['scope_opener'];
+        $outerScopeCloser = $tokens[$stackPtr]['scope_closer'];
+
+        $nextNonEmpty = $phpcsFile->findNext(Tokens::$emptyTokens, ($outerScopeOpener + 1), $outerScopeCloser, true);
+        if ($nextNonEmpty === false || $tokens[$nextNonEmpty]['code'] !== \T_IF) {
+            // Definitely not a lonely if statement.
+            return;
+        }
+
+        if (isset($tokens[$nextNonEmpty]['scope_closer']) === false) {
+            // Either a control structure without curly braces or a parse error. Ignore.
+            return;
+        }
+
+        /*
+         * Find the end of an if - else chain.
+         */
+        $innerIfPtr       = $nextNonEmpty;
+        $innerIfToken     = $tokens[$innerIfPtr];
+        $autoFixable      = true;
+        $innerScopeCloser = $innerIfToken['scope_closer'];
+
+        /*
+         * For alternative syntax fixer only.
+         * Remember the individual inner scope opener and closers so the fixer doesn't need
+         * to do the same walking over the if/else chain again.
+         */
+        $innerScopes = [
+            $innerIfToken['scope_opener'] => $innerScopeCloser,
+        ];
+
+        do {
+            /*
+             * Handle control structures using alternative syntax.
+             */
+            if ($tokens[$innerScopeCloser]['code'] !== \T_CLOSE_CURLY_BRACKET) {
+                if ($tokens[$innerScopeCloser]['code'] === \T_ENDIF) {
+                    $nextAfter = $phpcsFile->findNext(
+                        Tokens::$emptyTokens,
+                        ($innerScopeCloser + 1),
+                        $outerScopeCloser,
+                        true
+                    );
+
+                    if ($tokens[$nextAfter]['code'] === \T_SEMICOLON) {
+                        $innerScopeCloser = $nextAfter;
+                    } else {
+                        // Missing semi-colon. Report, but don't auto-fix.
+                        $autoFixable = false;
+                    }
+                } else {
+                    // This must be an else[if].
+                    --$innerScopeCloser;
+                }
+            }
+
+            $innerNextNonEmpty = $phpcsFile->findNext(
+                Tokens::$emptyTokens,
+                ($innerScopeCloser + 1),
+                $outerScopeCloser,
+                true
+            );
+            if ($innerNextNonEmpty === false) {
+                // This was the last closer.
+                break;
+            }
+
+            if ($tokens[$innerNextNonEmpty]['code'] !== \T_ELSE
+                && $tokens[$innerNextNonEmpty]['code'] !== \T_ELSEIF
+            ) {
+                // Found another statement after the control structure. The "if" is not lonely.
+                return;
+            }
+
+            if (isset($tokens[$innerNextNonEmpty]['scope_closer']) === false) {
+                // This may still be an "else if"...
+                $nextAfter = $phpcsFile->findNext(
+                    Tokens::$emptyTokens,
+                    ($innerNextNonEmpty + 1),
+                    $outerScopeCloser,
+                    true
+                );
+
+                if ($nextAfter === false
+                    || $tokens[$nextAfter]['code'] !== \T_IF
+                    || isset($tokens[$nextAfter]['scope_closer']) === false
+                ) {
+                    // Defense in depth. Either a control structure without curly braces or a parse error. Ignore.
+                    return;
+                }
+
+                $innerNextNonEmpty = $nextAfter;
+            }
+
+            $innerScopeCloser = $tokens[$innerNextNonEmpty]['scope_closer'];
+            $innerScopes[$tokens[$innerNextNonEmpty]['scope_opener']] = $innerScopeCloser;
+        } while (true);
+
+        /*
+         * As of now, we know we have an error. Check if it can be auto-fixed.
+         */
+        if ($phpcsFile->findNext(\T_WHITESPACE, ($innerScopeCloser + 1), $outerScopeCloser, true) !== false) {
+            // Comment between the inner and outer closers.
+            $autoFixable = false;
+        }
+
+        if ($tokens[$innerScopeCloser]['code'] === \T_SEMICOLON) {
+            $hasComment = $phpcsFile->findPrevious(\T_WHITESPACE, ($innerScopeCloser - 1), null, true);
+            if ($tokens[$hasComment]['code'] !== \T_ENDIF) {
+                // Comment between the "endif" and the semi-colon.
+                $autoFixable = false;
+            }
+        }
+
+        if ($tokens[$outerScopeOpener]['line'] !== $innerIfToken['line']) {
+            for ($startOfNextLine = ($outerScopeOpener + 1); $startOfNextLine < $innerIfPtr; $startOfNextLine++) {
+                if ($tokens[$outerScopeOpener]['line'] !== $tokens[$startOfNextLine]['line']) {
+                    break;
+                }
+            }
+
+            if ($phpcsFile->findNext(\T_WHITESPACE, $startOfNextLine, $innerIfPtr, true) !== false) {
+                // Comment between the inner and outer openers.
+                $autoFixable = false;
+            }
+        }
+
+        if (isset($innerIfToken['parenthesis_opener'], $innerIfToken['parenthesis_closer']) === false) {
+            // Start/end of the condition of the if unclear. Most likely a parse error.
+            $autoFixable = false;
+        }
+
+        /*
+         * Throw the error and potentially fix it.
+         */
+        $error = 'If control structure block found as the only statement within an "else" block. Use elseif instead.';
+        $code  = 'Found';
+
+        if ($autoFixable === false) {
+            $phpcsFile->addError($error, $stackPtr, $code);
+            return;
+        }
+
+        $fix = $phpcsFile->addFixableError($error, $stackPtr, $code);
+        if ($fix === false) {
+            return;
+        }
+
+        /*
+         * Fix it.
+         */
+        $outerInnerSameType = false;
+        if (($tokens[$outerScopeCloser]['code'] === \T_CLOSE_CURLY_BRACKET
+            && $tokens[$innerScopeCloser]['code'] === \T_CLOSE_CURLY_BRACKET)
+            || ($tokens[$outerScopeCloser]['code'] === \T_ENDIF
+            && $tokens[$innerScopeCloser]['code'] === \T_SEMICOLON)
+        ) {
+            $outerInnerSameType = true;
+        }
+
+        $targetIsCurly = ($tokens[$outerScopeCloser]['code'] === \T_CLOSE_CURLY_BRACKET);
+
+        $innerScopeCount = \count($innerScopes);
+
+        $condition = GetTokensAsString::origContent($phpcsFile, ($innerIfPtr + 1), ($innerIfToken['scope_opener'] - 1));
+        if ($targetIsCurly === true) {
+            $condition = \rtrim($condition) . ' ';
+        }
+
+        $phpcsFile->fixer->beginChangeset();
+
+        // Remove the inner if + condition up to and including the scope opener.
+        for ($i = $innerIfPtr; $i <= $innerIfToken['scope_opener']; $i++) {
+            $phpcsFile->fixer->replaceToken($i, '');
+        }
+
+        // Potentially remove trailing whitespace/new line if there is no comment after the inner condition.
+        while ($tokens[$i]['line'] === $innerIfToken['line']
+            && $tokens[$i]['code'] === \T_WHITESPACE
+        ) {
+            $phpcsFile->fixer->replaceToken($i, '');
+            ++$i;
+        }
+
+        // Remove any potential indentation whitespace for the inner if.
+        if ($tokens[$outerScopeOpener]['line'] !== $innerIfToken['line']
+            && $tokens[$i]['line'] !== $innerIfToken['line']
+        ) {
+            $i = ($nextNonEmpty - 1);
+            while ($tokens[$i]['line'] === $innerIfToken['line']
+                && $tokens[$i]['code'] === \T_WHITESPACE
+            ) {
+                $phpcsFile->fixer->replaceToken($i, '');
+                --$i;
+            }
+        }
+
+        // Remove the inner scope closer.
+            $phpcsFile->fixer->replaceToken($innerScopeCloser, '');
+        $i = ($innerScopeCloser - 1);
+
+        // Handle alternative syntax for the closer.
+        if ($tokens[$innerScopeCloser]['code'] === \T_SEMICOLON) {
+            // Remove potential whitespace between the "endif" and the semicolon.
+            while ($tokens[$i]['code'] === \T_WHITESPACE) {
+                $phpcsFile->fixer->replaceToken($i, '');
+                --$i;
+            }
+
+            // Remove the "endif".
+            $phpcsFile->fixer->replaceToken($i, '');
+            --$i;
+        }
+
+        // Remove superfluous whitespace before the inner scope closer.
+        while ($tokens[$i]['code'] === \T_WHITESPACE) {
+            $phpcsFile->fixer->replaceToken($i, '');
+            --$i;
+        }
+
+        // Replace the else.
+        $phpcsFile->fixer->replaceToken($stackPtr, 'elseif' . $condition);
+
+        // Remove potential superfluous whitespace between the new condition and the scope opener.
+        $i = ($stackPtr + 1);
+        while ($tokens[$i]['line'] === $tokens[$stackPtr]['line']
+            && $tokens[$i]['code'] === \T_WHITESPACE
+        ) {
+            $phpcsFile->fixer->replaceToken($i, '');
+            ++$i;
+        }
+
+        if ($outerInnerSameType === false
+            && $innerScopeCount > 1
+        ) {
+            $loop = 1;
+            foreach ($innerScopes as $opener => $closer) {
+                if ($targetIsCurly === true) {
+                    if ($loop !== 1) {
+                        // Only handle the opener when it's not the first of the chain as that's already handled above.
+                        $phpcsFile->fixer->replaceToken($opener, ' {');
+                    }
+
+                    if ($loop !== $innerScopeCount) {
+                        // Only handle the closer when it's not the last of the chain as that's already handled above.
+                        $phpcsFile->fixer->addContentBefore($closer, '} ');
+                    }
+                } else {
+                    if ($loop !== 1) {
+                        // Only handle the opener when it's not the first of the chain as that's already handled above.
+                        $phpcsFile->fixer->replaceToken($opener, ':');
+                    }
+
+                    if ($loop !== $innerScopeCount) {
+                        // Only handle the closer when it's not the last of the chain as that's already handled above.
+                        $phpcsFile->fixer->replaceToken($closer, '');
+
+                        $j = ($closer + 1);
+                        while ($tokens[$j]['code'] === \T_WHITESPACE) {
+                            $phpcsFile->fixer->replaceToken($j, '');
+                            ++$j;
+                        }
+                    }
+                }
+
+                ++$loop;
+            }
+        }
+
+        $phpcsFile->fixer->endChangeset();
+    }
+}
diff --git a/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.inc b/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.inc
new file mode 100644
index 00000000..c50a9d2c
--- /dev/null
+++ b/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.inc
@@ -0,0 +1,275 @@
+<?php
+
+/*
+ * Else blocks which don't have a lonely if statement.
+ */
+if ($condition) {
+    doSomething();
+} else if ($anotherCondition) {
+    doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) {
+    if ($subCondition) {
+        doSomething();
+    }
+} else {
+    doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    }
+
+    doSomethingElse();
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    doSomethingElse();
+
+    if ($anotherCondition) {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    }
+
+    if ($secondIf) {
+        doSomething();
+    }
+}
+
+/*
+ * Variations of If - else blocks without curly braces. Ignore.
+ */
+if ($condition)
+    doSomething();
+else
+    if ($anotherCondition)
+        doSomething();
+
+if ($condition)
+    doSomething();
+else
+    if ($anotherCondition) {
+        doSomething();
+    }
+
+if ($condition)
+    doSomething();
+else {
+    if ($anotherCondition)
+        doSomething();
+
+    doSomethingElse();
+}
+
+/*
+ * Lonely if statements in else blocks.
+ */
+if ($condition) { doSomething(); } else { if ($anotherCondition) { doSomething(); } }
+
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    } else {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    } else if ($yetAnotherCondition) {
+        doSomething();
+    } else {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    } elseif ($yetAnotherCondition) {
+        doSomething();
+    }
+}
+
+// Also test it with alternative syntax.
+if ($condition):
+    doSomething();
+else:
+    if ($anotherCondition):
+        doSomething();
+    endif;
+endif;
+
+if ($condition):
+    doSomething();
+else  :
+    if ($anotherCondition):
+        doSomething();
+    else:
+        doSomething();
+    endif  ;
+endif;
+
+if ($condition):
+    doSomething();
+else:
+    if ($anotherCondition):
+        doSomething();
+    elseif ($yetAnotherCondition):
+        doSomething();
+    else:
+        doSomething();
+    endif;
+endif;
+
+// Testing the fixing of mixed curly braces and alternative syntax.
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition):
+        doSomething();
+    elseif ($yetAnotherCondition):
+        doSomething();
+    else:
+        doSomething();
+    endif;
+}
+
+if ($condition):
+    doSomething();
+else:
+    if ($anotherCondition) {
+        doSomething();
+    } elseif ($yetAnotherCondition) {
+        doSomething();
+    } else {
+        doSomething();
+    }
+endif;
+
+/*
+ * Fixer specific test cases. Making sure the fixer handles comments correctly.
+ */
+if ($condition) { doSomething(); } else { if ($anotherCondition) { /* comment */ doSomething(); } }
+
+if ($condition) {
+    doSomething();
+} else /* comment */ {
+    if ($anotherCondition) {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} else { /* comment */
+    if ($anotherCondition) {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} else { /* comment */
+    if ($anotherCondition) { /* comment */
+        doSomething();
+    }
+}
+
+// Report, but leave unfixed. Unclear where the comment should go.
+if ($condition) {
+    doSomething();
+} else {
+    /* comment */
+    if ($anotherCondition) {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    if /* comment */ ($anotherCondition) {
+        doSomething();
+    }
+}
+
+// Report, but leave unfixed. Unclear where the comment should go.
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    } /* comment */
+}
+
+// Report, but leave unfixed. Unclear where the comment should go.
+if ($condition):
+    doSomething();
+else:
+    if ($anotherCondition):
+        doSomething();
+    endif /* comment */;
+endif;
+
+// Intentional parse error. Report, but leave unfixed.
+if ($condition):
+    doSomething();
+else:
+    if ($anotherCondition):
+        doSomething();
+    endif
+endif;
+
+// Empty else. Ignore.
+if ($a) {
+    doSomething();
+} else {}
+
+// Intentional parse error.
+if ($a) {
+    doSomething();
+} else {
+    if ($anotherCondition {
+        doSomething();
+    }
+}
+
+// Live coding.
+// Intentional parse error. This test has to be the last in the file.
+if ($a) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    }
diff --git a/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.inc.fixed b/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.inc.fixed
new file mode 100644
index 00000000..7e36e249
--- /dev/null
+++ b/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.inc.fixed
@@ -0,0 +1,250 @@
+<?php
+
+/*
+ * Else blocks which don't have a lonely if statement.
+ */
+if ($condition) {
+    doSomething();
+} else if ($anotherCondition) {
+    doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) {
+    if ($subCondition) {
+        doSomething();
+    }
+} else {
+    doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    }
+
+    doSomethingElse();
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    doSomethingElse();
+
+    if ($anotherCondition) {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    }
+
+    if ($secondIf) {
+        doSomething();
+    }
+}
+
+/*
+ * Variations of If - else blocks without curly braces. Ignore.
+ */
+if ($condition)
+    doSomething();
+else
+    if ($anotherCondition)
+        doSomething();
+
+if ($condition)
+    doSomething();
+else
+    if ($anotherCondition) {
+        doSomething();
+    }
+
+if ($condition)
+    doSomething();
+else {
+    if ($anotherCondition)
+        doSomething();
+
+    doSomethingElse();
+}
+
+/*
+ * Lonely if statements in else blocks.
+ */
+if ($condition) { doSomething(); } elseif ($anotherCondition) { doSomething(); }
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) {
+        doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) {
+        doSomething();
+    } else {
+        doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) {
+        doSomething();
+    } else if ($yetAnotherCondition) {
+        doSomething();
+    } else {
+        doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) {
+        doSomething();
+    } elseif ($yetAnotherCondition) {
+        doSomething();
+}
+
+// Also test it with alternative syntax.
+if ($condition):
+    doSomething();
+elseif ($anotherCondition):
+        doSomething();
+endif;
+
+if ($condition):
+    doSomething();
+elseif ($anotherCondition):
+        doSomething();
+    else:
+        doSomething();
+endif;
+
+if ($condition):
+    doSomething();
+elseif ($anotherCondition):
+        doSomething();
+    elseif ($yetAnotherCondition):
+        doSomething();
+    else:
+        doSomething();
+endif;
+
+// Testing the fixing of mixed curly braces and alternative syntax.
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) {
+        doSomething();
+    } elseif ($yetAnotherCondition) {
+        doSomething();
+    } else {
+        doSomething();
+}
+
+if ($condition):
+    doSomething();
+elseif ($anotherCondition) :
+        doSomething();
+    elseif ($yetAnotherCondition) :
+        doSomething();
+    else :
+        doSomething();
+endif;
+
+/*
+ * Fixer specific test cases. Making sure the fixer handles comments correctly.
+ */
+if ($condition) { doSomething(); } elseif ($anotherCondition) { /* comment */ doSomething(); }
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) /* comment */ {
+        doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) { /* comment */
+        doSomething();
+}
+
+if ($condition) {
+    doSomething();
+} elseif ($anotherCondition) { /* comment */
+    /* comment */
+        doSomething();
+}
+
+// Report, but leave unfixed. Unclear where the comment should go.
+if ($condition) {
+    doSomething();
+} else {
+    /* comment */
+    if ($anotherCondition) {
+        doSomething();
+    }
+}
+
+if ($condition) {
+    doSomething();
+} elseif /* comment */ ($anotherCondition) {
+        doSomething();
+}
+
+// Report, but leave unfixed. Unclear where the comment should go.
+if ($condition) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    } /* comment */
+}
+
+// Report, but leave unfixed. Unclear where the comment should go.
+if ($condition):
+    doSomething();
+else:
+    if ($anotherCondition):
+        doSomething();
+    endif /* comment */;
+endif;
+
+// Intentional parse error. Report, but leave unfixed.
+if ($condition):
+    doSomething();
+else:
+    if ($anotherCondition):
+        doSomething();
+    endif
+endif;
+
+// Empty else. Ignore.
+if ($a) {
+    doSomething();
+} else {}
+
+// Intentional parse error.
+if ($a) {
+    doSomething();
+} else {
+    if ($anotherCondition {
+        doSomething();
+    }
+}
+
+// Live coding.
+// Intentional parse error. This test has to be the last in the file.
+if ($a) {
+    doSomething();
+} else {
+    if ($anotherCondition) {
+        doSomething();
+    }
diff --git a/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.php b/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.php
new file mode 100644
index 00000000..46963e07
--- /dev/null
+++ b/Universal/Tests/ControlStructures/DisallowLonelyIfUnitTest.php
@@ -0,0 +1,69 @@
+<?php
+/**
+ * PHPCSExtra, a collection of sniffs and standards for use with PHP_CodeSniffer.
+ *
+ * @package   PHPCSExtra
+ * @copyright 2020 PHPCSExtra Contributors
+ * @license   https://opensource.org/licenses/LGPL-3.0 LGPL3
+ * @link      https://github.com/PHPCSStandards/PHPCSExtra
+ */
+
+namespace PHPCSExtra\Universal\Tests\ControlStructures;
+
+use PHP_CodeSniffer\Tests\Standards\AbstractSniffUnitTest;
+
+/**
+ * Unit test class for the DisallowLonelyIf sniff.
+ *
+ * @covers PHPCSExtra\Universal\Sniffs\ControlStructures\DisallowLonelyIfSniff
+ *
+ * @since 1.0.0
+ */
+class DisallowLonelyIfUnitTest extends AbstractSniffUnitTest
+{
+
+    /**
+     * Returns the lines where errors should occur.
+     *
+     * @return array <int line number> => <int number of errors>
+     */
+    public function getErrorList()
+    {
+        return [
+            // Basic checks.
+            82  => 1,
+            86  => 1,
+            94  => 1,
+            104 => 1,
+            116 => 1,
+
+            // Alternative control structure syntax.
+            127 => 1,
+            135 => 1,
+            145 => 1,
+            158 => 1,
+            170 => 1,
+
+            // Fixer specific tests with comments.
+            183 => 1,
+            187 => 1,
+            195 => 1,
+            203 => 1,
+            212 => 1,
+            221 => 1,
+            230 => 1,
+            239 => 1,
+            248 => 1,
+        ];
+    }
+
+    /**
+     * Returns the lines where warnings should occur.
+     *
+     * @return array <int line number> => <int number of warnings>
+     */
+    public function getWarningList()
+    {
+        return [];
+    }
+}