feat: Save default appmap.yml

.travis.yml

@@ -5,7 +5,6 @@ cache:
 - yarn
 
 rbenv:
-- 2.5
 - 2.6
 - 2.7
 - 3.0

appmap.gemspec

@@ -12,6 +12,8 @@ Gem::Specification.new do |spec|
   spec.authors       = ['Kevin Gilpin']
   spec.email         = ['[email protected]']
 
+  spec.required_ruby_version = '>= 2.6.0'
+
   spec.summary       = %q{Record the operation of a Ruby program, using the AppLand 'AppMap' format.}
   spec.homepage      = AppMap::URL
   spec.license       = 'MIT'

lib/appmap/config.rb

@@ -338,28 +338,34 @@ def load_from_file(config_file_name)
           AppMap uses this file to customize its behavior. For example, you can use
           the 'packages' setting to indicate which local file paths and dependency
           gems you want to include in the AppMap. Since you haven't provided specific
-          settings, the appmap gem will try and guess some reasonable defaults.
-          To suppress this message, create the file:
-
-          #{Pathname.new(config_file_name).expand_path}
-
-          Here are the default settings that will be used in the meantime. You can
-          copy and paste this example to start your appmap.yml.
+          settings, the appmap gem will use these default options:
           MISSING_FILE_MSG
           {}
         end
 
         load(config_data).tap do |config|
-          config_yaml = {
+          {
             'name' => config.name,
             'packages' => config.packages.select{|p| p.path}.map do |pkg|
               { 'path' => pkg.path }
             end,
             'exclude' => []
-          }.compact
-          unless config_present
-            warn Util.color(YAML.dump(config_yaml), :magenta)
-            warn logo.()
+          }.compact.tap do |config_yaml|
+            unless config_present
+              warn Util.color(YAML.dump(config_yaml), :magenta)
+              dirname = Pathname.new(config_file_name).dirname.expand_path
+              if Dir.exists?(dirname) && File.writable?(dirname)
+                warn Util.color(<<~CONFIG_FILE_MSG, :magenta)
+                This file will be saved to #{Pathname.new(config_file_name).expand_path},
+                where you can customize it.
+                CONFIG_FILE_MSG
+                File.write(config_file_name, YAML.dump(config_yaml))
+              end
+              warn Util.color(<<~CONFIG_FILE_MSG, :magenta)
+              For more information, see https://appmap.io/docs/reference/appmap-ruby.html#configuration
+              CONFIG_FILE_MSG
+              warn logo.()
+            end
           end
         end
       end

spec/config_spec.rb

@@ -130,13 +130,13 @@
     end
   end
 
-  context do
+  context 'missing config file' do
+    before { FileUtils.mkdir_p 'tmp' }
     let(:warnings) { @warnings ||= [] }
     let(:warning) { warnings.join }
-    before do
-      expect(AppMap::Config).to receive(:warn).at_least(1) { |msg| warnings << msg }
-    end
     it 'prints a warning and uses a default config' do
+      expect(AppMap::Config).to receive(:warn).at_least(1) { |msg| warnings << msg }
+
       config = AppMap::Config.load_from_file 'no/such/file'
       expect(config.to_h).to eq(YAML.load(<<~CONFIG))
       :name: appmap-ruby
@@ -150,5 +150,19 @@
       CONFIG
       expect(warning).to include('NOTICE: The AppMap config file no/such/file was not found!')
     end
+    describe 'writeable dir' do
+      it 'saves the guessed config' do
+        expect(File).to receive(:write).with("tmp/appmap.yml", instance_of(String))
+
+        AppMap::Config.load_from_file 'tmp/appmap.yml'
+      end
+    end
+    describe 'non-writeable dir' do
+      it 'does not save the guessed config' do
+        File.stub(:write).and_raise "Unexpected File.write"
+
+        config = AppMap::Config.load_from_file '/no/such/appmap.yml'
+      end
+    end
   end
 end