re-add support for loading aliases in yaml files

Ruby 3.1 includes Psych 4.0 which no longer loads aliases by default.
Since aliases are part of the yaml spec, it seems sensible to re-add
support.

We need to read the file first to be compatible with ruby2.7 which does
not support the aliases option on YAML.load_file. Use temp files in
rspec tests to avoid needing to mock read.

Author: lollipopman

Diff for: lib/puppet/parser/functions/loadyaml.rb

@@ -49,9 +49,12 @@ module Puppet::Parser::Functions
           warning("Can't load '#{url}' HTTP Error Code: '#{res.status[0]}'")
           args[1]
         end
-        YAML.safe_load(contents) || args[1]
+        YAML.safe_load(contents, aliases: true) || args[1]
       elsif File.exist?(args[0])
-        YAML.load_file(args[0]) || args[1]
+        # Read the file first rather than calling YAML.load_file as ruby2.7
+        # doesn't support the aliases option on YAML.load_file
+        contents = File.read(args[0])
+        YAML.safe_load(contents, aliases: true) || args[1]
       else
         warning("Can't load '#{args[0]}' File does not exist!")
         args[1]

Diff for: spec/functions/loadyaml_spec.rb

@@ -12,30 +12,48 @@
     it "'default' => 'value'" do
       allow(File).to receive(:exist?).and_call_original
       expect(File).to receive(:exist?).with(filename).and_return(false).once
-      expect(YAML).not_to receive(:load_file)
+      expect(YAML).not_to receive(:safe_load)
       expect(subject).to run.with_params(filename, 'default' => 'value').and_return('default' => 'value')
     end
   end
 
   context 'when an existing file is specified' do
-    let(:filename) { '/tmp/doesexist' }
+    let(:tempfile) { Tempfile.new }
+    let(:filename) { tempfile.path }
     let(:data) { { 'key' => 'value', 'ķęŷ' => 'νậŀųề', 'キー' => '値' } }
+    let(:yaml) do
+      <<~YAML
+        key: 'value'
+        ķęŷ: 'νậŀųề'
+        キー: '値'
+      YAML
+    end
 
     it "returns 'key' => 'value', 'ķęŷ' => 'νậŀųề', 'キー' => '値'" do
+      tempfile.write(yaml)
+      tempfile.rewind
       allow(File).to receive(:exist?).and_call_original
       expect(File).to receive(:exist?).with(filename).and_return(true).once
-      expect(YAML).to receive(:load_file).with(filename).and_return(data).once
+      expect(YAML).to receive(:safe_load).and_call_original
       expect(subject).to run.with_params(filename).and_return(data)
     end
   end
 
-  context 'when the file could not be parsed' do
-    let(:filename) { '/tmp/doesexist' }
+  context 'when the file could not be parsed, with default specified' do
+    let(:tempfile) { Tempfile.new }
+    let(:filename) { tempfile.path }
+    let(:yaml) do
+      <<~YAML
+        ,,,,
+      YAML
+    end
 
-    it 'filename /tmp/doesexist' do
+    it 'is expected to return the default value' do
+      tempfile.write(yaml)
+      tempfile.rewind
       allow(File).to receive(:exist?).and_call_original
       expect(File).to receive(:exist?).with(filename).and_return(true).once
-      allow(YAML).to receive(:load_file).with(filename).once.and_raise(StandardError, 'Something terrible have happened!')
+      allow(YAML).to receive(:safe_load).with(yaml, aliases: true).once.and_raise(StandardError, 'Something terrible have happened!')
       expect(subject).to run.with_params(filename, 'default' => 'value').and_return('default' => 'value')
     end
   end
@@ -48,7 +66,7 @@
 
     it {
       expect(OpenURI).to receive(:open_uri).with(filename, basic_auth).and_return(yaml)
-      expect(YAML).to receive(:safe_load).with(yaml).and_return(data).once
+      expect(YAML).to receive(:safe_load).with(yaml, aliases: true).and_return(data).once
       expect(subject).to run.with_params(filename).and_return(data)
     }
   end
@@ -62,7 +80,7 @@
 
     it {
       expect(OpenURI).to receive(:open_uri).with(url_no_auth, basic_auth).and_return(yaml)
-      expect(YAML).to receive(:safe_load).with(yaml).and_return(data).once
+      expect(YAML).to receive(:safe_load).with(yaml, aliases: true).and_return(data).once
       expect(subject).to run.with_params(filename).and_return(data)
     }
   end
@@ -76,7 +94,7 @@
 
     it {
       expect(OpenURI).to receive(:open_uri).with(url_no_auth, basic_auth).and_return(yaml)
-      expect(YAML).to receive(:safe_load).with(yaml).and_return(data).once
+      expect(YAML).to receive(:safe_load).with(yaml, aliases: true).and_return(data).once
       expect(subject).to run.with_params(filename).and_return(data)
     }
   end
@@ -88,7 +106,7 @@
 
     it {
       expect(OpenURI).to receive(:open_uri).with(filename, basic_auth).and_return(yaml)
-      expect(YAML).to receive(:safe_load).with(yaml).and_raise StandardError, 'Cannot parse data'
+      expect(YAML).to receive(:safe_load).with(yaml, aliases: true).and_raise StandardError, 'Cannot parse data'
       expect(subject).to run.with_params(filename, 'default' => 'value').and_return('default' => 'value')
     }
   end
@@ -103,4 +121,43 @@
       expect(subject).to run.with_params(filename, 'default' => 'value').and_return('default' => 'value')
     }
   end
+
+  context 'when the file contains aliases' do
+    let(:tempfile) { Tempfile.new }
+    let(:filename) { tempfile.path }
+    let(:yaml) do
+      <<~YAML
+        some_numbers: &nums
+          - one
+          - two
+        more_numbers: *nums
+      YAML
+    end
+    let(:data) { { 'some_numbers' => ['one', 'two'], 'more_numbers' => ['one', 'two'] } }
+
+    it 'parses the aliases' do
+      tempfile.write(yaml)
+      tempfile.rewind
+      expect(subject).to run.with_params(filename).and_return(data)
+    end
+  end
+
+  context 'when a URL returns yaml with aliases' do
+    let(:filename) { 'https://example.local/myhash.yaml' }
+    let(:basic_auth) { { http_basic_authentication: ['', ''] } }
+    let(:yaml) do
+      <<~YAML
+        some_numbers: &nums
+          - one
+          - two
+        more_numbers: *nums
+      YAML
+    end
+    let(:data) { { 'some_numbers' => ['one', 'two'], 'more_numbers' => ['one', 'two'] } }
+
+    it {
+      expect(OpenURI).to receive(:open_uri).with(filename, basic_auth).and_return(yaml)
+      expect(subject).to run.with_params(filename).and_return(data)
+    }
+  end
 end