Cognitive Complexity

Cognitive Complexity is a measure of how difficult a unit of code is to intuitively understand. Unlike Cyclomatic Complexity, which determines how difficult your code will be to test, Cognitive Complexity tells you how difficult your code will be to read and comprehend.

A method's cognitive complexity is based on a few simple rules:

• Code is not considered more complex when it uses shorthand that the language provides for collapsing multiple statements into one
• Code is considered more complex for each "break in the linear flow of the code"
• Code is considered more complex when "flow breaking structures are nested"

Further reading

• Cognitive Complexity docs
• Cognitive Complexity: A new way of measuring understandability

MD013 - Line length

Tags: line_length

Aliases: line-length Parameters: linelength, codeblocks, tables (number; default 80, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks and tables. To do this, set the code_blocks and/or tables parameters to false.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.

MD034 - Bare URL used

Tags: links, url

Aliases: no-bare-urls

This rule is triggered whenever a URL is given that isn't surrounded by angle brackets:

For more information, see http://www.example.com/.

To fix this, add angle brackets around the URL:

For more information, see <http:></http:>.

Rationale: Without angle brackets, the URL isn't converted into a link in many markdown parsers.

Note: if you do want a bare URL without it being converted into a link, enclose it in a code block, otherwise in some markdown parsers it will be converted:

`http://www.example.com`

MD024 - Multiple headers with the same content

Tags: headers

Aliases: no-duplicate-header

Parameters: allowdifferentnesting (boolean; default false)

This rule is triggered if there are multiple headers in the document that have the same text:

# Some text

## Some text

To fix this, ensure that the content of each header is different:

# Some text

## Some more text

Rationale: Some markdown parses generate anchors for headers based on the header name, and having headers with the same content can cause problems with this.

If the parameter allow_different_nesting is set to true, header duplication under different nesting is allowed, like it usually happens in change logs:

# Change log

## 2.0.0

### Bug fixes

### Features

## 1.0.0

### Bug fixes

MD032 - Lists should be surrounded by blank lines

Tags: bullet, ul, ol, blank_lines

Aliases: blanks-around-lists

This rule is triggered when lists (of any kind) are either not preceded or not followed by a blank line:

Some text
* Some
* List

1. Some
2. List
Some text

To fix this, ensure that all lists have a blank line both before and after (except where the block is at the beginning or end of the document):

Some text

* Some
* List

1. Some
2. List

Some text

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse lists that don't have blank lines before and after them.

Note: List items without hanging indents are a violation of this rule; list items with hanging indents are okay:

* This is
not okay

* This is
  okay

MD013 - Line length

Tags: line_length

Aliases: line-length Parameters: linelength, codeblocks, tables (number; default 80, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks and tables. To do this, set the code_blocks and/or tables parameters to false.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.

MD022 - Headers should be surrounded by blank lines

Tags: headers, blank_lines

Aliases: blanks-around-headers

This rule is triggered when headers (any style) are either not preceded or not followed by a blank line:

# Header 1
Some text

Some more text
## Header 2

To fix this, ensure that all headers have a blank line both before and after (except where the header is at the beginning or end of the document):

# Header 1

Some text

Some more text

## Header 2

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse headers that don't have a blank line before, and will parse them as regular text.

MD032 - Lists should be surrounded by blank lines

Tags: bullet, ul, ol, blank_lines

Aliases: blanks-around-lists

This rule is triggered when lists (of any kind) are either not preceded or not followed by a blank line:

Some text
* Some
* List

1. Some
2. List
Some text

To fix this, ensure that all lists have a blank line both before and after (except where the block is at the beginning or end of the document):

Some text

* Some
* List

1. Some
2. List

Some text

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse lists that don't have blank lines before and after them.

Note: List items without hanging indents are a violation of this rule; list items with hanging indents are okay:

* This is
not okay

* This is
  okay

MD022 - Headers should be surrounded by blank lines

Tags: headers, blank_lines

Aliases: blanks-around-headers

This rule is triggered when headers (any style) are either not preceded or not followed by a blank line:

# Header 1
Some text

Some more text
## Header 2

To fix this, ensure that all headers have a blank line both before and after (except where the header is at the beginning or end of the document):

# Header 1

Some text

Some more text

## Header 2

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse headers that don't have a blank line before, and will parse them as regular text.

MD022 - Headers should be surrounded by blank lines

Tags: headers, blank_lines

Aliases: blanks-around-headers

This rule is triggered when headers (any style) are either not preceded or not followed by a blank line:

# Header 1
Some text

Some more text
## Header 2

To fix this, ensure that all headers have a blank line both before and after (except where the header is at the beginning or end of the document):

# Header 1

Some text

Some more text

## Header 2

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse headers that don't have a blank line before, and will parse them as regular text.

MD013 - Line length

Tags: line_length

Aliases: line-length Parameters: linelength, codeblocks, tables (number; default 80, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks and tables. To do this, set the code_blocks and/or tables parameters to false.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.

MD034 - Bare URL used

Tags: links, url

Aliases: no-bare-urls

This rule is triggered whenever a URL is given that isn't surrounded by angle brackets:

For more information, see http://www.example.com/.

To fix this, add angle brackets around the URL:

For more information, see <http:></http:>.

Rationale: Without angle brackets, the URL isn't converted into a link in many markdown parsers.

Note: if you do want a bare URL without it being converted into a link, enclose it in a code block, otherwise in some markdown parsers it will be converted:

`http://www.example.com`

MD013 - Line length

Tags: line_length

Aliases: line-length Parameters: linelength, codeblocks, tables (number; default 80, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks and tables. To do this, set the code_blocks and/or tables parameters to false.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.

MD013 - Line length

Tags: line_length

Aliases: line-length Parameters: linelength, codeblocks, tables (number; default 80, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks and tables. To do this, set the code_blocks and/or tables parameters to false.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.

MD024 - Multiple headers with the same content

Tags: headers

Aliases: no-duplicate-header

Parameters: allowdifferentnesting (boolean; default false)

This rule is triggered if there are multiple headers in the document that have the same text:

# Some text

## Some text

To fix this, ensure that the content of each header is different:

# Some text

## Some more text

Rationale: Some markdown parses generate anchors for headers based on the header name, and having headers with the same content can cause problems with this.

If the parameter allow_different_nesting is set to true, header duplication under different nesting is allowed, like it usually happens in change logs:

# Change log

## 2.0.0

### Bug fixes

### Features

## 1.0.0

### Bug fixes

MD024 - Multiple headers with the same content

Tags: headers

Aliases: no-duplicate-header

Parameters: allowdifferentnesting (boolean; default false)

This rule is triggered if there are multiple headers in the document that have the same text:

# Some text

## Some text

To fix this, ensure that the content of each header is different:

# Some text

## Some more text

Rationale: Some markdown parses generate anchors for headers based on the header name, and having headers with the same content can cause problems with this.

If the parameter allow_different_nesting is set to true, header duplication under different nesting is allowed, like it usually happens in change logs:

# Change log

## 2.0.0

### Bug fixes

### Features

## 1.0.0

### Bug fixes

MD024 - Multiple headers with the same content

Tags: headers

Aliases: no-duplicate-header

Parameters: allowdifferentnesting (boolean; default false)

This rule is triggered if there are multiple headers in the document that have the same text:

# Some text

## Some text

To fix this, ensure that the content of each header is different:

# Some text

## Some more text

Rationale: Some markdown parses generate anchors for headers based on the header name, and having headers with the same content can cause problems with this.

If the parameter allow_different_nesting is set to true, header duplication under different nesting is allowed, like it usually happens in change logs:

# Change log

## 2.0.0

### Bug fixes

### Features

## 1.0.0

### Bug fixes

MD013 - Line length

Tags: line_length

Aliases: line-length Parameters: linelength, codeblocks, tables (number; default 80, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks and tables. To do this, set the code_blocks and/or tables parameters to false.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.

MD013 - Line length

Tags: line_length

Aliases: line-length Parameters: linelength, codeblocks, tables (number; default 80, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks and tables. To do this, set the code_blocks and/or tables parameters to false.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.