This warning comes up if a model does not limit what attributes can be set through mass assignment.

In particular, this check looks for attr_accessible inside model definitions. If it is not found, this warning will be issued.

Brakeman also warns on use of attr_protected - especially since it was found to be vulnerable to bypass. Warnings for mass assignment on models using attr_protected will be reported, but at a lower confidence level.

Note that disabling mass assignment globally will suppress these warnings.

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

This cop checks for the use of output safety calls like htmlsafe, raw, and safeconcat. These methods do not escape content. They simply return a SafeBuffer containing the content as is. Instead, use safe_join to join content and escape it and concat to concatenate content and escape it, ensuring its safety.

Example:

user_content = "hi"

# bad
"
#{user_content}
".html_safe
# => ActiveSupport::SafeBuffer "
hi
"

# good
content_tag(:p, user_content)
# => ActiveSupport::SafeBuffer "
<b>hi</b>
"

# bad
out = ""
out << "
#{user_content}
"
out << "
#{user_content}
"
out.html_safe
# => ActiveSupport::SafeBuffer "
hi
hi
"

# good
out = []
out << content_tag(:li, user_content)
out << content_tag(:li, user_content)
safe_join(out)
# => ActiveSupport::SafeBuffer
#    "
<b>hi</b>
<b>hi</b>
"

# bad
out = "
trusted content
".html_safe
out.safe_concat(user_content)
# => ActiveSupport::SafeBuffer "
trusted_content
hi"

# good
out = "
trusted content
".html_safe
out.concat(user_content)
# => ActiveSupport::SafeBuffer
#    "
trusted_content
<b>hi</b>"

# safe, though maybe not good style
out = "trusted content"
result = out.concat(user_content)
# => String "trusted contenthi"
# because when rendered in ERB the String will be escaped:
# <%= result %>
# => trusted content<b>hi</b>

# bad
(user_content + " " + content_tag(:span, user_content)).html_safe
# => ActiveSupport::SafeBuffer "hi <span><b>hi</b></span>"

# good
safe_join([user_content, " ", content_tag(:span, user_content)])
# => ActiveSupport::SafeBuffer
#    "<b>hi</b> <span>&lt;b&gt;hi&lt;/b&gt;</span>"

This cop checks for the use of output safety calls like htmlsafe, raw, and safeconcat. These methods do not escape content. They simply return a SafeBuffer containing the content as is. Instead, use safe_join to join content and escape it and concat to concatenate content and escape it, ensuring its safety.

Example:

user_content = "hi"

# bad
"
#{user_content}
".html_safe
# => ActiveSupport::SafeBuffer "
hi
"

# good
content_tag(:p, user_content)
# => ActiveSupport::SafeBuffer "
<b>hi</b>
"

# bad
out = ""
out << "
#{user_content}
"
out << "
#{user_content}
"
out.html_safe
# => ActiveSupport::SafeBuffer "
hi
hi
"

# good
out = []
out << content_tag(:li, user_content)
out << content_tag(:li, user_content)
safe_join(out)
# => ActiveSupport::SafeBuffer
#    "
<b>hi</b>
<b>hi</b>
"

# bad
out = "
trusted content
".html_safe
out.safe_concat(user_content)
# => ActiveSupport::SafeBuffer "
trusted_content
hi"

# good
out = "
trusted content
".html_safe
out.concat(user_content)
# => ActiveSupport::SafeBuffer
#    "
trusted_content
<b>hi</b>"

# safe, though maybe not good style
out = "trusted content"
result = out.concat(user_content)
# => String "trusted contenthi"
# because when rendered in ERB the String will be escaped:
# <%= result %>
# => trusted content<b>hi</b>

# bad
(user_content + " " + content_tag(:span, user_content)).html_safe
# => ActiveSupport::SafeBuffer "hi <span><b>hi</b></span>"

# good
safe_join([user_content, " ", content_tag(:span, user_content)])
# => ActiveSupport::SafeBuffer
#    "<b>hi</b> <span>&lt;b&gt;hi&lt;/b&gt;</span>"

This cop checks whether the end keywords are aligned properly.

Three modes are supported through the EnforcedStyleAlignWith configuration parameter:

If it's set to keyword (which is the default), the end shall be aligned with the start of the keyword (if, class, etc.).

If it's set to variable the end shall be aligned with the left-hand-side of the variable assignment, if there is one.

If it's set to start_of_line, the end shall be aligned with the start of the line where the matching keyword appears.

Example: EnforcedStyleAlignWith: keyword (default)

# bad

variable = if true
    end

# good

variable = if true
           end

Example: EnforcedStyleAlignWith: variable

# bad

variable = if true
    end

# good

variable = if true
end

Example: EnforcedStyleAlignWith: startofline

# bad

variable = if true
    end

# good

puts(if true
end)

This cop checks for duplicated instance (or singleton) method definitions.

Example:

# bad

def duplicated
  1
end

def duplicated
  2
end

Example:

# bad

def duplicated
  1
end

alias duplicated other_duplicated

Example:

# good

def duplicated
  1
end

def other_duplicated
  2
end