Fix formula reporter inconsistencies

Library/Homebrew/api.rb

@@ -216,7 +216,7 @@ module Homebrew
       names_path = HOMEBREW_CACHE_API/"#{type}_names.txt"
       if !names_path.exist? || regenerate
         names_path.unlink if names_path.exist?
-        names_path.write(names.join("\n"))
+        names_path.write(names.sort.join("\n"))
         return true
       end
 
@@ -231,7 +231,7 @@ module Homebrew
           "#{alias_name}|#{real_name}"
         end
         aliases_path.unlink if aliases_path.exist?
-        aliases_path.write(aliases_text.join("\n"))
+        aliases_path.write(aliases_text.sort.join("\n"))
         return true
       end
 

Library/Homebrew/cmd/update-report.rb

@@ -785,14 +785,27 @@ class Reporter
 
       api_dir_prefix_basename = T.must(api_dir_prefix).basename
 
-      diff_output.lines.filter_map do |line|
+      diff_hash = diff_output.lines.each_with_object({}) do |line, hash|
         next if line.match?(header_regex)
         next unless add_delete_characters.include?(line[0])
 
-        line.sub(/^\+/, "A #{api_dir_prefix_basename}/")
-            .sub(/^-/,  "D #{api_dir_prefix_basename}/")
-            .sub(/$/,   ".rb")
-            .chomp
+        name = line.chomp.delete_prefix("+").delete_prefix("-")
+        file = "#{api_dir_prefix_basename}/#{name}.rb"
+
+        hash[file] ||= 0
+        if line.start_with?("+")
+          hash[file] += 1
+        elsif line.start_with?("-")
+          hash[file] -= 1
+        end
+      end
+
+      diff_hash.filter_map do |file, count|
+        if count.positive?
+          "A #{file}"
+        elsif count.negative?
+          "D #{file}"
+        end
       end.join("\n")
     else
       Utils.popen_read(

Library/Homebrew/test/cmd/update-report_spec.rb

@@ -152,6 +152,45 @@ RSpec.describe Homebrew::Cmd::UpdateReport do
         expect(tap.cask_tokens).to include("new-cask")
       end
     end
+
+    describe "#diff" do
+      context "when using the API" do
+        subject(:reporter) do
+          described_class.new(tap,
+                              api_names_txt:        Pathname("formula_names.txt"),
+                              api_names_before_txt: Pathname("formula_names_before.txt"),
+                              api_dir_prefix:       HOMEBREW_CACHE/"api")
+        end
+
+        it "ignore lines that haven't changed" do
+          expect(Utils).to receive(:popen_read).and_return(<<~DIFF)
+            foo
+            +bar
+            -baz
+          DIFF
+
+          expect(reporter.send(:diff)).to eq(<<~DIFF.strip)
+            A api/bar.rb
+            D api/baz.rb
+          DIFF
+        end
+
+        it "handles moved lines" do
+          expect(Utils).to receive(:popen_read).and_return(<<~DIFF)
+            +baz
+            foo
+            +bar
+            +baz
+            -bar
+            -baz
+          DIFF
+
+          expect(reporter.send(:diff)).to eq(<<~DIFF.strip)
+            A api/baz.rb
+          DIFF
+        end
+      end
+    end
   end
 
   describe ReporterHub do