(CONT-675) Fix fact detection

Prior to this change the legacy facts check would not detect legacy
facts defined as follows:

```
$::facts['osfamily']
````

This changes updates the `check` logic to evaluate tokens that may start
with `::` and extract the fact name as appropriate.
`

lib/puppet-lint/plugins/legacy_facts/legacy_facts.rb

@@ -115,19 +115,25 @@ def check
     tokens.select { |x| LEGACY_FACTS_VAR_TYPES.include?(x.type) }.each do |token|
       fact_name = ''
 
-      # Get rid of the top scope before we do our work. We don't need to
-      # preserve it because it won't work with the new structured facts.
-      if token.value.start_with?('::')
-        fact_name = token.value.sub(%r{^::}, '')
+      # This matches legacy facts defined in the fact hash that use the top scope
+      # fact assignment.
+      if token.value.start_with?('::facts[')
+        fact_name = token.value.match(%r{::facts\['(.*)'\]})[1]
+
+      # This matches legacy facts defined in the fact hash.
+      elsif token.value.start_with?("facts['")
+        fact_name = token.value.match(%r{facts\['(.*)'\]})[1]
 
       # This matches using legacy facts in a the new structured fact. For
       # example this would match 'uuid' in $facts['uuid'] so it can be converted
       # to facts['dmi']['product']['uuid']"
       elsif token.value == 'facts'
         fact_name = hash_key_for(token)
 
-      elsif token.value.start_with?("facts['")
-        fact_name = token.value.match(%r{facts\['(.*)'\]})[1]
+      # Now we can get rid of top scopes. We don't need to
+      # preserve it because it won't work with the new structured facts.
+      elsif token.value.start_with?('::')
+        fact_name = token.value.sub(%r{^::}, '')
       end
 
       next unless EASY_FACTS.include?(fact_name) || UNCONVERTIBLE_FACTS.include?(fact_name) || fact_name.match(Regexp.union(REGEX_FACTS))

spec/unit/puppet-lint/plugins/legacy_facts/legacy_facts_spec.rb

@@ -113,6 +113,14 @@
         expect(problems).to have(1).problem
       end
     end
+
+    context 'top scoped fact variable using legacy facts hash variable in interpolation' do
+      let(:code) { "$::facts['osfamily']" }
+
+      it 'detects a single problem' do
+        expect(problems).to have(1).problem
+      end
+    end
   end
 
   context 'with fix enabled' do
@@ -165,6 +173,23 @@
       end
     end
 
+    context "fact variable using legacy $::facts['osfamily']" do
+      let(:code) { "$::facts['osfamily']" }
+      let(:msg) { "legacy fact 'osfamily'" }
+
+      it 'only detects a single problem' do
+        expect(problems).to have(1).problem
+      end
+
+      it 'fixes the problem' do
+        expect(problems).to contain_fixed(msg).on_line(1).in_column(1)
+      end
+
+      it 'uses the facts hash' do
+        expect(manifest).to eq("$facts['os']['family']")
+      end
+    end
+
     context 'fact variable using legacy $::osfamily' do
       let(:code) { '$::osfamily' }
       let(:msg) { "legacy fact 'osfamily'" }