FormulaAuditor: Add #collect_previous_info method

The `#audit_stable_version` check was previously part of
`#audit_revision_and_version_scheme` and duplicates some of the
logic to identify previous version information. To avoid the
duplication, this extracts the logic into a `#collect_previous_info`
method that can be called in both audits. The method stores the
information in instance variables, so we don't repeat the collection
process if it has already run.

Library/Homebrew/formula_auditor.rb

@@ -37,6 +37,8 @@ def initialize(formula, options = {})
       @spdx_license_data = options[:spdx_license_data]
       @spdx_exception_data = options[:spdx_exception_data]
       @tap_audit = options[:tap_audit]
+      @previous = {}
+      @newest_committed = {}
     end
 
     def audit_style
@@ -782,39 +784,13 @@ def audit_stable_version
 
       current_version = formula.stable.version
       current_version_scheme = formula.version_scheme
-      current_revision = formula.revision
-
-      previous_version = T.let(nil, T.nilable(Version))
-      previous_version_scheme = T.let(nil, T.nilable(Integer))
-      previous_revision = T.let(nil, T.nilable(Integer))
-
-      newest_committed_version = T.let(nil, T.nilable(Version))
-
-      fv = FormulaVersions.new(formula)
-      fv.rev_list("origin/HEAD") do |revision, path|
-        begin
-          fv.formula_at_revision(revision, path) do |f|
-            stable = f.stable
-            next if stable.blank?
-
-            previous_version = stable.version
-            previous_version_scheme = f.version_scheme
-            previous_revision = f.revision
-
-            newest_committed_version ||= previous_version
-          end
-        rescue MacOSVersion::Error
-          break
-        end
 
-        break if previous_version && current_version != previous_version
-        break if previous_revision && current_revision != previous_revision
-      end
+      collect_previous_info
 
-      if !newest_committed_version.nil? &&
-         current_version < newest_committed_version &&
-         current_version_scheme == previous_version_scheme
-        problem "stable version should not decrease (from #{newest_committed_version} to #{current_version})"
+      if !@newest_committed[:version].nil? &&
+         current_version < @newest_committed[:version] &&
+         current_version_scheme == @previous[:version_scheme]
+        problem "stable version should not decrease (from #{@newest_committed[:version]} to #{current_version})"
       end
     end
 
@@ -832,72 +808,40 @@ def audit_revision_and_version_scheme
       current_revision = formula.revision
       current_url = formula.stable.url
 
-      previous_version = T.let(nil, T.nilable(Version))
-      previous_version_scheme = T.let(nil, T.nilable(Integer))
-      previous_revision = T.let(nil, T.nilable(Integer))
-
-      newest_committed_version = T.let(nil, T.nilable(Version))
-      newest_committed_checksum = T.let(nil, T.nilable(String))
-      newest_committed_revision = T.let(nil, T.nilable(Integer))
-      newest_committed_url = T.let(nil, T.nilable(String))
-
-      fv = FormulaVersions.new(formula)
-      fv.rev_list("origin/HEAD") do |revision, path|
-        begin
-          fv.formula_at_revision(revision, path) do |f|
-            stable = f.stable
-            next if stable.blank?
-
-            previous_version = stable.version
-            previous_checksum = stable.checksum
-            previous_version_scheme = f.version_scheme
-            previous_revision = f.revision
-
-            newest_committed_version ||= previous_version
-            newest_committed_checksum ||= previous_checksum
-            newest_committed_revision ||= previous_revision
-            newest_committed_url ||= stable.url
-          end
-        rescue MacOSVersion::Error
-          break
-        end
-
-        break if previous_version && current_version != previous_version
-        break if previous_revision && current_revision != previous_revision
-      end
+      collect_previous_info
 
-      if current_version == newest_committed_version &&
-         current_url == newest_committed_url &&
-         current_checksum != newest_committed_checksum &&
-         current_checksum.present? && newest_committed_checksum.present?
+      if current_version == @newest_committed[:version] &&
+         current_url == @newest_committed[:url] &&
+         current_checksum != @newest_committed[:checksum] &&
+         current_checksum.present? && @newest_committed[:checksum].present?
         problem(
           "stable sha256 changed without the url/version also changing; " \
           "please create an issue upstream to rule out malicious " \
           "circumstances and to find out why the file changed.",
         )
       end
 
-      unless previous_version_scheme.nil?
-        if current_version_scheme < previous_version_scheme
-          problem "version_scheme should not decrease (from #{previous_version_scheme} " \
+      unless @previous[:version_scheme].nil?
+        if current_version_scheme < @previous[:version_scheme]
+          problem "version_scheme should not decrease (from #{@previous[:version_scheme]} " \
                   "to #{current_version_scheme})"
-        elsif current_version_scheme > (previous_version_scheme + 1)
+        elsif current_version_scheme > (@previous[:version_scheme] + 1)
           problem "version_schemes should only increment by 1"
         end
       end
 
-      if (previous_version != newest_committed_version ||
-         current_version != newest_committed_version) &&
+      if (@previous[:version] != @newest_committed[:version] ||
+         current_version != @newest_committed[:version]) &&
          !current_revision.zero? &&
-         current_revision == newest_committed_revision &&
-         current_revision == previous_revision
+         current_revision == @newest_committed[:revision] &&
+         current_revision == @previous[:revision]
         problem "'revision #{current_revision}' should be removed"
-      elsif current_version == previous_version &&
-            !previous_revision.nil? &&
-            current_revision < previous_revision
-        problem "revision should not decrease (from #{previous_revision} to #{current_revision})"
-      elsif newest_committed_revision &&
-            current_revision > (newest_committed_revision + 1)
+      elsif current_version == @previous[:version] &&
+            !@previous[:revision].nil? &&
+            current_revision < @previous[:revision]
+        problem "revision should not decrease (from #{@previous[:revision]} to #{current_revision})"
+      elsif @newest_committed[:revision] &&
+            current_revision > (@newest_committed[:revision] + 1)
         problem "revisions should only increment by 1"
       end
     end
@@ -1005,5 +949,43 @@ def linux_only_gcc_dep?(formula)
 
       true
     end
+
+    def collect_previous_info
+      return if formula.stable.blank?
+      return if @previous.present? || @newest_committed.present?
+
+      current_version = formula.stable.version
+      current_revision = formula.revision
+
+      fv = FormulaVersions.new(formula)
+      fv.rev_list("origin/HEAD") do |revision, path|
+        begin
+          fv.formula_at_revision(revision, path) do |f|
+            stable = f.stable
+            next if stable.blank?
+
+            @previous[:version] = stable.version
+            @previous[:checksum] = stable.checksum
+            @previous[:version_scheme] = f.version_scheme
+            @previous[:revision] = f.revision
+
+            @newest_committed[:version] ||= @previous[:version]
+            @newest_committed[:checksum] ||= @previous[:checksum]
+            @newest_committed[:revision] ||= @previous[:revision]
+            @newest_committed[:url] ||= stable.url
+          end
+        rescue MacOSVersion::Error
+          break
+        end
+
+        break if @previous[:version] && current_version != @previous[:version]
+        break if @previous[:revision] && current_revision != @previous[:revision]
+      end
+
+      @previous.compact!
+      @newest_committed.compact!
+
+      nil
+    end
   end
 end