audit: Port audit_checksum method to rubocop and add tests

2 files changed, 57 insertions, 3 deletions

diff --git a/Library/Homebrew/rubocops/checksum_cop.rb b/Library/Homebrew/rubocops/checksum_cop.rb
new file mode 100644
index 000000000..98e6a8bd3
--- /dev/null
+++ b/Library/Homebrew/rubocops/checksum_cop.rb
@@ -0,0 +1,55 @@
+require_relative "./extend/formula_cop"
+
+module RuboCop
+  module Cop
+    module FormulaAudit
+      class Checksum < FormulaCop
+        def audit_formula(_node, _class_node, _parent_class_node, body_node)
+          %w[Stable Devel HEAD].each do |name|
+            next unless spec_node = find_block(body_node, name.downcase.to_sym)
+            _, _, spec_body = *spec_node
+            audit_checksums(spec_body, name)
+            resource_blocks = find_all_blocks(spec_body, :resource)
+            resource_blocks.each do |rb|
+              _, _, resource_body = *rb
+              audit_checksums(resource_body, name, string_content(parameters(rb).first))
+            end
+          end
+        end
+
+        def audit_checksums(node, spec, resource_name = nil)
+          msg_prefix = if resource_name
+            "#{spec} resource \"#{resource_name}\": "
+          else
+            "#{spec}: "
+          end
+          if find_node_method_by_name(node, :md5)
+            problem "#{msg_prefix}MD5 checksums are deprecated, please use SHA256"
+          end
+
+          if find_node_method_by_name(node, :sha1)
+            problem "#{msg_prefix}SHA1 checksums are deprecated, please use SHA256"
+          end
+
+          checksum_node = find_node_method_by_name(node, :sha256)
+          checksum = parameters(checksum_node).first
+          if string_content(checksum).size.zero?
+            problem "#{msg_prefix}sha256 is empty"
+            return
+          end
+
+          if string_content(checksum).size != 64 && regex_match_group(checksum, /^\w*$/)
+            problem "#{msg_prefix}sha256 should be 64 characters"
+          end
+
+          unless regex_match_group(checksum, /^[a-f0-9]+$/i)
+            problem "#{msg_prefix}sha256 contains invalid characters"
+          end
+
+          return unless regex_match_group(checksum, /^[a-f0-9]+$/)
+          problem "#{msg_prefix}sha256 should be lowercase"
+        end
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/rubocops/extend/formula_cop.rb b/Library/Homebrew/rubocops/extend/formula_cop.rb
index 6bb406c05..b6fa45d3f 100644
--- a/Library/Homebrew/rubocops/extend/formula_cop.rb
+++ b/Library/Homebrew/rubocops/extend/formula_cop.rb
@@ -176,7 +176,7 @@ module RuboCop
       # Returns an array of block nodes of any depth below node in AST
       def find_all_blocks(node, block_name)
         return if node.nil?
-        node.each_descendant(:block).select { |block_node| block_name == block_node.method_name}
+        node.each_descendant(:block).select { |block_node| block_name == block_node.method_name }
       end
 
       # Returns a method definition node with method_name
@@ -256,8 +256,7 @@ module RuboCop
 
       # Returns the array of arguments of the method_node
       def parameters(method_node)
-        return unless method_node.send_type? || method_node.block_type?
-        method_node.method_args
+        method_node.method_args if method_node.send_type? || method_node.block_type?
       end
 
       # Returns true if the given parameters are present in method call