Fix service-diff command

The problem here was that for some reason on CI the hashicorp tap
is installed and that means that I was running this command for that
tap too. This didn't really make any sense because we only really
need to run this command for the core tap; nothing else gets serialized
to the API.

I removed the --tap= command and now it just runs on the core tap by
default which should help us avoid this problem.

I tested it both with all formulae in the core tap and a single formula.

README.md

@@ -92,7 +92,6 @@ Warning: This command runs git commands on the main brew repo. To be safe avoid
 running other brew commands simultaneously.
 
       --formula                    Run the diff on only one formula.
-      --tap                        Run the diff on only one tap.
       --word-diff                  Show word diff instead of default line diff.
       --stat                       Shows condensed output based on git
                                    diff --stat

cmd/service-diff.rb

@@ -17,11 +17,9 @@ class ServiceDiff < AbstractCommand
         EOS
 
         flag "--formula=", description: "Run the diff on only one formula."
-        flag "--tap=", description: "Run the diff on only one tap."
         switch "--word-diff", description: "Show word diff instead of default line diff."
         switch "--stat", description: "Shows condensed output based on `git diff --stat`"
 
-        conflicts "--tap=", "--formula="
         conflicts "--word-diff", "--stat"
       end
 
@@ -32,9 +30,7 @@ def run
         odie "Script #{script_path} doesn't exist!" unless File.exist?(script_path)
 
         script_args =
-          if args.tap
-            ["tap", args.tap]
-          elsif args.formula
+          if args.formula
             ["formula", args.formula]
           else
             ["all"]

lib/diff-scripts/service_diff.rb

@@ -11,12 +11,11 @@
 # Expects:
 # 1. Command type from VALID_COMMAND_TYPES
 # 2. Command arg
-#    - for command type `tap` it should be the name of a tap
 #    - for command type `formula` it should be the name of a formula
 #    - for command type `all` it is NOT necessary
 COMMAND_TYPE, COMMAND_ARG, *extra = ARGV
 
-VALID_COMMAND_TYPES = %w[all tap formula].freeze
+VALID_COMMAND_TYPES = %w[all formula].freeze
 
 if VALID_COMMAND_TYPES.exclude?(COMMAND_TYPE)
   odie "Unknown command type `#{COMMAND_TYPE}`!"
@@ -29,9 +28,9 @@
 FORMULAE =
   case COMMAND_TYPE
   when "all"
-    Formula.all(eval_all: true)
-  when "tap"
-    Tap.fetch(COMMAND_ARG).formula_files.map(&Formulary.method(:factory))
+    CoreTap.instance.formula_names.map do |name|
+      Formulary.factory(name)
+    end
   when "formula"
     [Formulary.factory(COMMAND_ARG)]
   end