rubocop: The pyyaml resource requires depends_on "libyaml"

Library/Homebrew/rubocops/resource_requires_dependencies.rb

@@ -6,7 +6,7 @@
 module RuboCop
   module Cop
     module FormulaAudit
-      # This cop audits Python formulae that include the "lxml" resource
+      # This cop audits Python formulae that include certain resources
       # to ensure that they also have the correct `uses_from_macos`
       # dependencies.
       #
@@ -16,15 +16,31 @@ def audit_formula(_node, _class_node, _parent_class_node, body_node)
           return if body_node.nil?
 
           resource_nodes = find_every_method_call_by_name(body_node, :resource)
-          lxml = resource_nodes.find { |node| node.arguments.first.str_content == "lxml" }
-          return unless lxml
+          return if resource_nodes.empty?
 
-          uses_from_macos_nodes = find_every_method_call_by_name(body_node, :uses_from_macos)
-          dependencies = uses_from_macos_nodes.map { |node| node.arguments.first.str_content }
-          return if dependencies.include?("libxml2") && dependencies.include?("libxslt")
+          %w[lxml pyyaml].each do |resource_name|
+            found = resource_nodes.find { |node| node.arguments.first.str_content == resource_name }
+            next unless found
 
-          offending_node(lxml)
-          problem "Add `uses_from_macos` lines above for `\"libxml2\"` and `\"libxslt\"`."
+            uses_from_macos_nodes = find_every_method_call_by_name(body_node, :uses_from_macos)
+            uses_from_macos = uses_from_macos_nodes.map { |node| node.arguments.first.str_content }
+
+            depends_on_nodes = find_every_method_call_by_name(body_node, :depends_on)
+            depends_on = depends_on_nodes.map { |node| node.arguments.first.str_content }
+
+            required_deps = case resource_name
+            when "lxml"
+              kind = "uses_from_macos"
+              ["libxml2", "libxslt"]
+            when "pyyaml"
+              kind = "depends_on"
+              ["libyaml"]
+            end
+            next if required_deps.all? { |dep| uses_from_macos.include?(dep) || depends_on.include?(dep) }
+
+            offending_node(found)
+            problem "Add `#{kind}` lines above for #{required_deps.map { |req| "`\"#{req}\"`" }.join(" and ")}."
+          end
         end
       end
     end

Library/Homebrew/test/rubocops/resource_requires_dependencies_spec.rb

@@ -5,6 +5,19 @@
 RSpec.describe RuboCop::Cop::FormulaAudit::ResourceRequiresDependencies do
   subject(:cop) { described_class.new }
 
+  context "when a formula does not have any resources" do
+    it "does not report offenses" do
+      expect_no_offenses(<<~RUBY)
+        class Foo < Formula
+          url "https://brew.sh/foo-1.0.tgz"
+          homepage "https://brew.sh"
+
+          uses_from_macos "libxml2"
+        end
+      RUBY
+    end
+  end
+
   context "when a formula does not have the lxml resource" do
     it "does not report offenses" do
       expect_no_offenses(<<~RUBY)
@@ -59,4 +72,84 @@ class Foo < Formula
       RUBY
     end
   end
+
+  context "when a formula does not have the pyyaml resource" do
+    it "does not report offenses" do
+      expect_no_offenses(<<~RUBY)
+        class Foo < Formula
+          url "https://brew.sh/foo-1.0.tgz"
+          homepage "https://brew.sh"
+
+          uses_from_macos "libxml2"
+
+          resource "not-pyyaml" do
+            url "blah"
+            sha256 "blah"
+          end
+        end
+      RUBY
+    end
+  end
+
+  context "when a formula has the pyyaml resource" do
+    it "does not report offenses if the dependencies are present" do
+      expect_no_offenses(<<~RUBY)
+        class Foo < Formula
+          url "https://brew.sh/foo-1.0.tgz"
+          homepage "https://brew.sh"
+
+          depends_on "libyaml"
+
+          resource "pyyaml" do
+            url "blah"
+            sha256 "blah"
+          end
+        end
+      RUBY
+    end
+
+    it "reports offenses if missing a dependency" do
+      expect_offense(<<~RUBY)
+        class Foo < Formula
+          url "https://brew.sh/foo-1.0.tgz"
+          homepage "https://brew.sh"
+
+          depends_on "not_libyaml"
+
+          resource "pyyaml" do
+          ^^^^^^^^^^^^^^^^^ FormulaAudit/ResourceRequiresDependencies: Add `depends_on` lines above for `"libyaml"`.
+            url "blah"
+            sha256 "blah"
+          end
+        end
+      RUBY
+    end
+  end
+
+  context "when a formula has multiple resources" do
+    it "reports offenses for each resource that is missing a dependency" do
+      expect_offense(<<~RUBY)
+        class Foo < Formula
+          url "https://brew.sh/foo-1.0.tgz"
+          homepage "https://brew.sh"
+
+          uses_from_macos "one"
+          uses_from_macos "two"
+          depends_on "three"
+
+          resource "lxml" do
+          ^^^^^^^^^^^^^^^ FormulaAudit/ResourceRequiresDependencies: Add `uses_from_macos` lines above for `"libxml2"` and `"libxslt"`.
+            url "blah"
+            sha256 "blah"
+          end
+
+          resource "pyyaml" do
+          ^^^^^^^^^^^^^^^^^ FormulaAudit/ResourceRequiresDependencies: Add `depends_on` lines above for `"libyaml"`.
+            url "blah"
+            sha256 "blah"
+          end
+        end
+      RUBY
+    end
+  end
 end