audit: Port audit_checksum method to rubocop and add tests

Library/.rubocop.yml

@@ -12,6 +12,9 @@ FormulaAudit/Text:
 FormulaAudit/Caveats:
   Enabled: true
 
+FormulaAudit/Checksum:
+  Enabled: true
+
 FormulaAuditStrict/BottleBlock:
   Enabled: true
 

Library/Homebrew/dev-cmd/audit.rb

@@ -1246,7 +1246,6 @@ def initialize(resource, options = {})
 
   def audit
     audit_version
-    audit_checksum
     audit_download_strategy
     audit_urls
     self
@@ -1273,28 +1272,6 @@ def audit_version
     problem "version #{version} should not end with an underline and a number"
   end
 
-  def audit_checksum
-    return unless checksum
-
-    case checksum.hash_type
-    when :md5
-      problem "MD5 checksums are deprecated, please use SHA256"
-      return
-    when :sha1
-      problem "SHA1 checksums are deprecated, please use SHA256"
-      return
-    when :sha256 then len = 64
-    end
-
-    if checksum.empty?
-      problem "#{checksum.hash_type} is empty"
-    else
-      problem "#{checksum.hash_type} should be #{len} characters" unless checksum.hexdigest.length == len
-      problem "#{checksum.hash_type} contains invalid characters" unless checksum.hexdigest =~ /^[a-fA-F0-9]+$/
-      problem "#{checksum.hash_type} should be lowercase" unless checksum.hexdigest == checksum.hexdigest.downcase
-    end
-  end
-
   def audit_download_strategy
     if url =~ %r{^(cvs|bzr|hg|fossil)://} || url =~ %r{^(svn)\+http://}
       problem "Use of the #{$&} scheme is deprecated, pass `:using => :#{$1}` instead"

Library/Homebrew/rubocops.rb

@@ -5,3 +5,4 @@
 require_relative "./rubocops/homepage_cop"
 require_relative "./rubocops/text_cop"
 require_relative "./rubocops/caveats_cop"
+require_relative "./rubocops/checksum_cop"

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

Library/Homebrew/rubocops/extend/formula_cop.rb

@@ -167,12 +167,18 @@ def find_block(node, block_name)
         nil
       end
 
-      # Returns an array of block nodes named block_name inside node
+      # Returns an array of block nodes of depth first order named block_name below node
       def find_blocks(node, block_name)
         return if node.nil?
         node.each_child_node(:block).select { |block_node| block_name == block_node.method_name }
       end
 
+      # 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 }
+      end
+
       # Returns a method definition node with method_name
       def find_method_def(node, method_name)
         return if node.nil?
@@ -250,8 +256,7 @@ def caveats_strings
 
       # Returns the array of arguments of the method_node
       def parameters(method_node)
-        return unless method_node.send_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

Library/Homebrew/test/rubocops/checksum_cop_spec.rb

@@ -0,0 +1,78 @@
+require "rubocop"
+require "rubocop/rspec/support"
+require_relative "../../extend/string"
+require_relative "../../rubocops/checksum_cop"
+
+describe RuboCop::Cop::FormulaAudit::Checksum do
+  subject(:cop) { described_class.new }
+
+  context "When auditing spec checksums" do
+    it "When the checksum is empty" do
+      source = <<-EOS.undent
+        class Foo < Formula
+          url 'http://example.com/foo-1.0.tgz'
+          stable do
+            url "https://github.com/foo-lang/foo-compiler/archive/0.18.0.tar.gz"
+            sha256 ""
+
+            resource "foo-package" do
+              url "https://github.com/foo-lang/foo-package/archive/0.18.0.tar.gz"
+              sha256 ""
+            end
+          end
+        end
+      EOS
+
+      expected_offenses = [{  message: "Stable: sha256 is empty",
+                              severity: :convention,
+                              line: 5,
+                              column: 4,
+                              source: source },
+                           {  message: "Stable resource \"foo-package\": sha256 is empty",
+                              severity: :convention,
+                              line: 9,
+                              column: 6,
+                              source: source }]
+
+      inspect_source(cop, source)
+
+      expected_offenses.zip(cop.offenses).each do |expected, actual|
+        expect_offense(expected, actual)
+      end
+    end
+
+    it "When the checksum is not 64 characters" do
+      source = <<-EOS.undent
+        class Foo < Formula
+          url 'http://example.com/foo-1.0.tgz'
+          stable do
+            url "https://github.com/foo-lang/foo-compiler/archive/0.18.0.tar.gz"
+            sha256 "5cf6e1ae0a645b426c0474cc7cd3f7d1605ffa1ac5756a39a8b2268ddc7ea0e9ad"
+
+            resource "foo-package" do
+              url "https://github.com/foo-lang/foo-package/archive/0.18.0.tar.gz"
+              sha256 "5cf6e1ae0a645b426c047aaa4cc7cd3f7d1605ffa1ac5756a39a8b2268ddc7ea0e9"
+            end
+          end
+        end
+      EOS
+
+      expected_offenses = [{  message: "Stable: sha256 should be 64 characters",
+                              severity: :convention,
+                              line: 5,
+                              column: 12,
+                              source: source },
+                           {  message: "Stable resource \"foo-package\": sha256 should be 64 characters",
+                              severity: :convention,
+                              line: 9,
+                              column: 14,
+                              source: source }]
+
+      inspect_source(cop, source)
+
+      expected_offenses.zip(cop.offenses).each do |expected, actual|
+        expect_offense(expected, actual)
+      end
+    end
+  end
+end