Remove support for ruby 2.1, 2.2, 2.3 and 2.4, add 2.6 instead

all older than 2.3 are already EOL and 2.4 will be EOL soon and the next
diaspora major version will already depend on newer versions, so we can
already remove it now.

.rubocop.yml

@@ -1,5 +1,5 @@
 AllCops:
-  TargetRubyVersion: 2.1
+  TargetRubyVersion: 2.5
   Exclude:
     - "bin/**/*"
     - "test/dummy/bin/**/*"

.ruby-version

@@ -1 +1 @@
-2.4
+2.6

.travis.yml

@@ -1,20 +1,12 @@
 language: ruby
 
 rvm:
-  - 2.5.5
+  - 2.6.5
-  - 2.4.5
+  - 2.5.7
-  - 2.3.8
-  - 2.2.10
-  - 2.1
 gemfile:
   - Gemfile
   - test/gemfiles/no-rails.Gemfile
 
-matrix:
-  exclude:
-    - rvm: 2.1
-      gemfile: Gemfile
-
 sudo: false
 cache:
   bundler: true

diaspora_federation-rails.gemspec

@@ -17,7 +17,7 @@ Gem::Specification.new do |s|
   s.files       = Dir["app/**/*", "config/routes.rb", "config/initializers/*",
                       "lib/diaspora_federation/{engine,rails}.rb", "LICENSE", "README.md", "Changelog.md"]
 
-  s.required_ruby_version = "~> 2.1"
+  s.required_ruby_version = "~> 2.5"
 
   s.add_dependency "actionpack", ">= 5", "< 6"
 

diaspora_federation-test.gemspec

@@ -17,7 +17,7 @@ Gem::Specification.new do |s|
 
   s.files       = Dir["lib/diaspora_federation/test.rb", "lib/diaspora_federation/test/*"]
 
-  s.required_ruby_version = "~> 2.1"
+  s.required_ruby_version = "~> 2.5"
 
   s.add_dependency "diaspora_federation", DiasporaFederation::VERSION
   s.add_dependency "fabrication", "~> 2.16"

diaspora_federation.gemspec

@@ -22,7 +22,7 @@ Gem::Specification.new do |s|
                         "lib/diaspora_federation/test/*",
                         "lib/tasks/*.rake"]
 
-  s.required_ruby_version = "~> 2.1"
+  s.required_ruby_version = "~> 2.5"
 
   s.add_dependency "faraday", ">= 0.9.0", "< 0.16.0"
   s.add_dependency "faraday_middleware", ">= 0.10.0", "< 0.14.0"

lib/diaspora_federation/entities/account_migration.rb

@@ -43,7 +43,7 @@ module DiasporaFederation
       # Returns diaspora* ID of the new person identity.
       # @return [String] diaspora* ID of the new person identity
       def new_identity
-        profile.author if profile
+        profile&.author
       end
 
       # @return [String] string representation of this object

lib/diaspora_federation/entities/participation.rb

@@ -35,7 +35,7 @@ module DiasporaFederation
       # Validates that the parent exists and the parent author is local
       def validate_parent
         parent = DiasporaFederation.callbacks.trigger(:fetch_related_entity, parent_type, parent_guid)
-        raise ParentNotLocal, "obj=#{self}" unless parent && parent.local
+        raise ParentNotLocal, "obj=#{self}" unless parent&.local
       end
 
       # Validate that the parent is local.

lib/diaspora_federation/validators/rules/birthday.rb

@@ -20,7 +20,7 @@ module Validation
         return true if value.nil? || (value.is_a?(String) && value.empty?)
         return true if value.is_a? Date
 
-        if value =~ /[0-9]{4}\-[0-9]{2}\-[0-9]{2}/
+        if value.is_a?(String) && value.match?(/[0-9]{4}\-[0-9]{2}\-[0-9]{2}/)
           date_field = value.split("-").map(&:to_i)
           return Date.valid_civil?(date_field[0], date_field[1], date_field[2])
         end

lib/tasks/gemfiles.rake

@@ -8,7 +8,6 @@ namespace :gemfiles do
     original_gemfile.sub!(/(gemspec name:.*)/) { "#{Regexp.last_match[1]}, path: \"../../\"" }
     original_gemfile.sub!(/(gemspec\(name:.*)\)/) { "#{Regexp.last_match[1]}, path: \"../../\")" }
     original_gemfile.sub!(/^group :development do$.*?^end$\n\n/m, "")
-    original_gemfile << "\n gem \"fabrication\", \"< 2.17.0\"\n" # new versions are not compatible with ruby 2.1
 
     no_rails_gemfile = original_gemfile.dup
     no_rails_gemfile.sub!(/(gemspec\(name:.*)/) { "#{Regexp.last_match[1]} unless plugin == \"rails\"" }