Improve cask audit

- check for cask.url in audit steps
- check for cask.version in audit steps
- check for cask.sha256 in fetch command
- stop omitting casks based on nil url in audit command

It would be nice to be able to omit casks from the audit
if the os is not supported but there is not easy way to
do that without updating the SimulateSystem code or
refactoring how MacOSRequirement's are defined in the DSL.

Library/Homebrew/cask/audit.rb

@@ -226,6 +226,7 @@ def audit_no_string_version_latest
     sig { void }
     def audit_sha256_no_check_if_latest
       return unless cask.sha256
+      return unless cask.version
 
       odebug "Auditing sha256 :no_check with version :latest"
       return unless cask.version.latest?
@@ -268,7 +269,7 @@ def audit_sha256_invalid
 
     sig { void }
     def audit_latest_with_livecheck
-      return unless cask.version.latest?
+      return unless cask.version&.latest?
       return unless cask.livecheckable?
       return if cask.livecheck.skip?
 
@@ -277,7 +278,7 @@ def audit_latest_with_livecheck
 
     sig { void }
     def audit_latest_with_auto_updates
-      return unless cask.version.latest?
+      return unless cask.version&.latest?
       return unless cask.auto_updates
 
       add_error "Casks with `version :latest` should not use `auto_updates`."
@@ -288,7 +289,8 @@ def audit_latest_with_auto_updates
     sig { params(livecheck_result: T.any(NilClass, T::Boolean, Symbol)).void }
     def audit_hosting_with_livecheck(livecheck_result: audit_livecheck_version)
       return if cask.discontinued?
-      return if cask.version.latest?
+      return if cask.version&.latest?
+      return unless cask.url
       return if block_url_offline?
       return if cask.livecheckable?
       return if livecheck_result == :auto_detected
@@ -328,6 +330,7 @@ def audit_download_url_format
 
     sig { void }
     def audit_unnecessary_verified
+      return unless cask.url
       return if block_url_offline?
       return unless verified_present?
       return unless url_match_homepage?
@@ -340,6 +343,7 @@ def audit_unnecessary_verified
 
     sig { void }
     def audit_missing_verified
+      return unless cask.url
       return if block_url_offline?
       return if file_url?
       return if url_match_homepage?
@@ -352,6 +356,7 @@ def audit_missing_verified
 
     sig { void }
     def audit_no_match
+      return unless cask.url
       return if block_url_offline?
       return unless verified_present?
       return if verified_matches_url?
@@ -453,6 +458,7 @@ def audit_download
 
     sig { void }
     def audit_livecheck_unneeded_long_version
+      return if cask.version.nil? || cask.url.nil?
       return if cask.livecheck.strategy != :sparkle
       return unless cask.version.csv.second
       return if cask.url.to_s.include? cask.version.csv.second
@@ -506,6 +512,7 @@ def audit_signing
     sig { returns(T.any(NilClass, T::Boolean, Symbol)) }
     def audit_livecheck_version
       return unless online?
+      return unless cask.version
 
       referenced_cask, = Homebrew::Livecheck.resolve_livecheck_reference(cask)
 

Library/Homebrew/cask/download.rb

@@ -36,6 +36,8 @@ def checksum
 
     sig { override.returns(T.nilable(Version)) }
     def version
+      return if cask.version.nil?
+
       @version ||= Version.new(cask.version)
     end
 

Library/Homebrew/cmd/fetch.rb

@@ -166,7 +166,7 @@ def self.fetch
           SimulateSystem.with os: os, arch: arch do
             cask = Cask::CaskLoader.load(ref)
 
-            if cask.url.nil?
+            if cask.url.nil? || cask.sha256.nil?
               opoo "Cask #{cask} is not supported on os #{os} and arch #{arch}"
               next
             end

Library/Homebrew/dev-cmd/audit.rb

@@ -242,17 +242,10 @@ def self.audit
         next [] if os == :linux
 
         SimulateSystem.with os: os, arch: arch do
-          simulated_cask = Cask::CaskLoader.load(path)
-
-          if simulated_cask.url.nil?
-            opoo "Cask #{cask} is not supported on os #{os} and arch #{arch}"
-            next []
-          end
-
           odebug "Auditing Cask #{cask} on os #{os} and arch #{arch}"
 
           Cask::Auditor.audit(
-            simulated_cask,
+            Cask::CaskLoader.load(path),
             # For switches, we add `|| nil` so that `nil` will be passed
             # instead of `false` if they aren't set.
             # This way, we can distinguish between "not set" and "set to false".