Do not query for the exact facter version

This assumes that no exact match can be found in most cases. This saves
a call to FacterDB. Some testing on puppet-nginx this reduced the time
for a dry run by about 1 to 2 seconds, from about ~11 to ~9 seconds.

Implementation wise this switches to using Gem::Requirement to detect
matching versions. This means you can also specify `~> 3.8` as a valid
facterversion, or `>= 3 < 5`.

lib/rspec-puppet-facts.rb

@@ -113,32 +113,31 @@ def on_supported_os_implementation(opts = {})
       end
     end
 
-    facterversion_obj = Gem::Version.new(facterversion)
+    # TODO: what if facterversion is a complex expression
+    exact_match = Gem::Version.new(facterversion)
+    facter_requirement = Gem::Requirement.new(RspecPuppetFacts::facter_version_to_requirement(facterversion))
 
     # FacterDB may have newer versions of facter data for which it contains a subset of all possible
     # facter data (see FacterDB 0.5.2 for Facter releases 3.8 and 3.9). In this situation we need to
     # cycle through and downgrade Facter versions per platform type until we find matching Facter data.
     filter.each do |filter_spec|
-      facter_version_filter = RspecPuppetFacts.facter_version_to_filter(facterversion)
-      db = FacterDB.get_facts(filter_spec.merge({ :facterversion =>  facter_version_filter }))
+      versions = FacterDB.get_facts(filter_spec).map { |facts| Gem::Version.new(facts[:facterversion]) }.sort.reverse
+      next unless versions.any?
 
-      if db.empty?
+      version = versions.include?(exact_match) ? exact_match : versions.detect { |v| facter_requirement =~ v }
+
+      next unless version
+      version = version.to_s
+
+      unless version == facterversion
         if RspecPuppetFacts.spec_facts_strict?
           raise ArgumentError, "No facts were found in the FacterDB for Facter v#{facterversion} on #{filter_spec}, aborting"
         end
 
-        version = FacterDB.get_facts(filter_spec).map { |facts| Gem::Version.new(facts[:facterversion]) }.sort.reverse.detect { |v| v <= facterversion_obj }
-
-        next unless version
-        version = version.to_s
-        facter_version_filter = "/\\A#{Regexp.escape(version)}/"
-
-        unless version == facterversion
-          RspecPuppetFacts.warning "No facts were found in the FacterDB for Facter v#{facterversion} on #{filter_spec}, using v#{version} instead"
-        end
+        RspecPuppetFacts.warning "No facts were found in the FacterDB for Facter v#{facterversion} on #{filter_spec}, using v#{version} instead"
       end
 
-      filter_spec[:facterversion] = facter_version_filter
+      filter_spec[:facterversion] = "/\\A#{Regexp.escape(version)}\\Z/"
     end
 
     received_facts = FacterDB::get_facts(filter)
@@ -353,13 +352,19 @@ def self.reset
     @metadata = nil
   end
 
-  # Generates a JGrep statement expression for a specific facter version
-  # @return [String] JGrep statement expression
-  # @param version [String] the Facter version
+  # Construct the facter version requirement
+  # @return [String] The version requirement to match
   # @api private
-  def self.facter_version_to_filter(version)
-    major, minor = version.split('.')
-    "/\\A#{major}\\.#{minor}\\./"
+  def self.facter_version_to_requirement(version)
+    if (m = /\A(?<major>[0-9]+)\.(?<minor>[0-9]+)(?:\.(?<patch>[0-9]+))?\Z/.match(version))
+      # Interpret 3.1 as < 3.2 and 3.2.1 as < 3.3
+      "< #{m[:major]}.#{m[:minor].to_i + 1}"
+    elsif /\A[0-9]+\Z/.match?(version)
+      # Interpret 3 as < 4
+      "< #{version.to_i + 1}"
+    else
+      version
+    end
   end
 
   def self.facter_version_for_puppet_version(puppet_version)

spec/rspec_puppet_facts_spec.rb

@@ -689,7 +689,7 @@
       end
 
       before do
-        RSpec.configuration.default_facter_version = '3.1.0'
+        RSpec.configuration.default_facter_version = '3.1.6'
       end
 
       after do
@@ -721,11 +721,10 @@
       end
 
 
-      it 'returns facts from a facter version matching future and below' do
-        major, minor = Facter.version.split('.')
+      it 'returns facts from a facter version matching version and below' do
         is_expected.to match(
           'centos-7-x86_64' => include(
-            :facterversion => /\A#{major}\.[#{minor}#{minor.to_i + 1}]\./,
+            :facterversion => /\A2\.[0-6]\./,
           ),
         )
       end
@@ -862,7 +861,7 @@
 
       it 'returns CentOS facts from a facter version matching 3.8' do
         is_expected.to include(
-          'centos-7-x86_64' => include(:facterversion => '3.8.0'),
+          'centos-7-x86_64' => include(:facterversion => '3.9.6'),
         )
       end
 
@@ -976,68 +975,108 @@ module MCollectiveStub # rubocop:todo Lint/ConstantDefinitionInBlock
     end
   end
 
-  describe '.facter_version_to_filter' do
+  describe '.facter_version_to_requirement' do
+    context 'when passed a version that is a complex requirement (1)' do
+      subject { described_class.facter_version_to_requirement('~> 2.4') }
+
+      it 'returns the correct expression' do
+        is_expected.to eq('~> 2.4')
+      end
+    end
+
+    context 'when passed a version that is a complex requirement (2)' do
+      subject { described_class.facter_version_to_requirement('>= 3 < 5') }
+
+      it 'returns the correct expression' do
+        is_expected.to eq('>= 3 < 5')
+      end
+    end
+
+    context 'when passed a version that is major (1)' do
+      subject { described_class.facter_version_to_requirement('1') }
+
+      it 'returns the correct expression' do
+        is_expected.to eq('< 2')
+      end
+    end
+
+    context 'when passed a version that is major (2)' do
+      subject { described_class.facter_version_to_requirement('9') }
+
+      it 'returns the correct expression' do
+        is_expected.to eq('< 10')
+      end
+    end
+
+    context 'when passed a version that is major (3)' do
+      subject { described_class.facter_version_to_requirement('10') }
+
+      it 'returns the correct expression' do
+        is_expected.to eq('< 11')
+      end
+    end
+
     context 'when passed a version that is major.minor (1)' do
-      subject { described_class.facter_version_to_filter('1.2') }
+      subject { described_class.facter_version_to_requirement('1.2') }
 
-      it 'returns the correct JGrep statement expression' do
-        is_expected.to eq('/\A1\.2\./')
+      it 'returns the correct expression' do
+        is_expected.to eq('< 1.3')
       end
     end
 
     context 'when passed a version that is major.minor (2)' do
-      subject { described_class.facter_version_to_filter('10.2') }
+      subject { described_class.facter_version_to_requirement('10.2') }
 
-      it 'returns the correct JGrep statement expression' do
-        is_expected.to eq('/\A10\.2\./')
+      it 'returns the correct expression' do
+        is_expected.to eq('< 10.3')
       end
     end
 
     context 'when passed a version that is major.minor (3)' do
-      subject { described_class.facter_version_to_filter('1.20') }
+      subject { described_class.facter_version_to_requirement('1.20') }
 
-      it 'returns the correct JGrep statement expression' do
-        is_expected.to eq('/\A1\.20\./')
+      it 'returns the correct expression' do
+        is_expected.to eq('< 1.21')
       end
     end
 
     context 'when passed a version that is major.minor (4)' do
-      subject { described_class.facter_version_to_filter('10.20') }
+      subject { described_class.facter_version_to_requirement('10.20') }
 
-      it 'returns the correct JGrep statement expression' do
-        is_expected.to eq('/\A10\.20\./')
+      it 'returns the correct expression' do
+        is_expected.to eq('< 10.21')
       end
     end
 
     context 'when passed a version that is major.minor.patch (1)' do
-      subject { described_class.facter_version_to_filter('1.2.3') }
+      subject { described_class.facter_version_to_requirement('1.2.3') }
 
-      it 'returns the correct JGrep statement expression' do
-        is_expected.to eq('/\A1\.2\./')
+      it 'returns the correct expression' do
+        is_expected.to eq('< 1.3')
       end
     end
 
     context 'when passed a version that is major.minor.patch (2)' do
-      subject { described_class.facter_version_to_filter('10.2.3') }
+      subject { described_class.facter_version_to_requirement('10.2.3') }
 
-      it 'returns the correct JGrep statement expression' do
-        is_expected.to eq('/\A10\.2\./')
+      it 'returns the correct expression' do
+        is_expected.to eq('< 10.3')
       end
     end
 
     context 'when passed a version that is major.minor.patch (3)' do
-      subject { described_class.facter_version_to_filter('1.20.3') }
+      subject { described_class.facter_version_to_requirement('1.20.3') }
 
-      it 'returns the correct JGrep statement expression' do
-        is_expected.to eq('/\A1\.20\./')
+      it 'returns the correct expression' do
+        is_expected.to eq('< 1.21')
       end
     end
 
     context 'when passed a version that is major.minor.patch (4)' do
-      subject { described_class.facter_version_to_filter('10.20.3') }
+      subject { described_class.facter_version_to_requirement('10.20.3') }
 
-      it 'returns the correct JGrep statement expression' do
-        is_expected.to eq('/\A10\.20\./')
+      it 'returns the correct expression' do
+        is_expected.to eq('< 10.21')
       end
     end
   end