Add symlink tests

Author: ianfixes

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Explicit checks for attemping to test `arduino_ci` itself as if it were a library, resolving a minor annoyance to this developer.
 - Code coverage tooling
 - Explicit check and warning for library directory names that do not match our guess of what the library should/would be called
+- Symlink tests for `Host`
 
 ### Changed
 - Arduino backend is now `arduino-cli` version `0.13.0`

exe/arduino_ci.rb

@@ -157,7 +157,7 @@ def file_is_hidden_somewhere?(path)
 # print out some files
 def display_files(pathname)
   # `find` doesn't follow symlinks, so we should instead
-  realpath = pathname.symlink? ? pathname.readlink : pathname
+  realpath = Host.symlink?(pathname) ? Host.readlink(pathname) : pathname
 
   # suppress directories and dotfile-based things
   all_files = realpath.find.select(&:file?)

lib/arduino_ci/arduino_backend.rb

@@ -196,7 +196,7 @@ def install_local_library(path)
 
         uhoh = "There is already a library '#{library_name}' in the library directory (#{destination_path})"
         # maybe it's a symlink? that would be OK
-        if destination_path.symlink?
+        if Host.symlink?(destination_path)
           return cpp_library if destination_path.readlink == src_path
 
           @last_msg = "#{uhoh} and it's not symlinked to #{src_path}"

lib/arduino_ci/host.rb

@@ -6,6 +6,10 @@ module ArduinoCI
 
   # Tools for interacting with the host machine
   class Host
+    # TODO: this came from https://stackoverflow.com/a/22716582/2063546
+    #       and I'm not sure if it can be replaced by self.os == :windows
+    WINDOWS_VARIANT_REGEX = /mswin32|cygwin|mingw|bccwin/.freeze
+
     # Cross-platform way of finding an executable in the $PATH.
     # via https://stackoverflow.com/a/5471032/2063546
     #   which('ruby') #=> /usr/bin/ruby
@@ -38,13 +42,15 @@ def self.os
       return :windows if OS.windows?
     end
 
+    # Cross-platform symlinking
     # if on windows, call mklink, else self.symlink
     # @param [Pathname] old_path
     # @param [Pathname] new_path
     def self.symlink(old_path, new_path)
-      return FileUtils.ln_s(old_path.to_s, new_path.to_s) unless RUBY_PLATFORM =~ /mswin32|cygwin|mingw|bccwin/
+      # we would prefer `new_path.make_symlink(old_path)` but "symlink function is unimplemented on this machine" with windows
+      return new_path.make_symlink(old_path) unless RUBY_PLATFORM =~ WINDOWS_VARIANT_REGEX
 
-      # https://stackoverflow.com/a/22716582/2063546
+      # via https://stackoverflow.com/a/22716582/2063546
       # windows mklink syntax is reverse of unix ln -s
       # windows mklink is built into cmd.exe
       # vulnerable to command injection, but okay because this is a hack to make a cli tool work.
@@ -54,5 +60,36 @@ def self.symlink(old_path, new_path)
       _stdout, _stderr, exitstatus = Open3.capture3('cmd.exe', "/C mklink /D #{np} #{orp}")
       exitstatus.success?
     end
+
+    # Cross-platform is-this-a-symlink function
+    # @param [Pathname] path
+    # @return [String] the output of a dir command
+    def self.get_windows_link_info(path)
+      # via https://stackoverflow.com/a/22716582/2063546
+      # vulnerable to command injection, but okay because this is a hack to make a cli tool work.
+      np = path.to_s.tr("/", "\\") # work around Pathname bug
+
+      stdout, _stderr, _exitstatus = Open3.capture3('cmd.exe', "/c dir #{np}")
+      puts "get_windows_link_info got:\n#{stdout}"
+      stdout
+    end
+
+    # Cross-platform is-this-a-symlink function
+    # @param [Pathname] path
+    # @return [bool] Whether the file is a symlink
+    def self.symlink?(path)
+      return path.symlink? unless RUBY_PLATFORM =~ WINDOWS_VARIANT_REGEX
+
+      get_windows_link_info.include?("SYMLINK")
+    end
+
+    # Cross-platform "read link" function
+    # @param [Pathname] path
+    # @return [Pathname] the link target
+    def self.readlink(path)
+      return path.readlink unless RUBY_PLATFORM =~ WINDOWS_VARIANT_REGEX
+
+      get_windows_link_info
+    end
   end
 end

spec/host_spec.rb

@@ -0,0 +1,20 @@
+require "spec_helper"
+
+RSpec.describe ArduinoCI::Host do
+  next if skip_ruby_tests
+
+  context "symlinks" do
+    it "creates symlinks that we agree are symlinks" do
+      Tempfile.create('arduinoci_symlink_test') do |file|
+        new_path = Pathname.new(file)
+        new_path.unlink # we just want the guaranteed-unique name, really
+
+        expect(new_path.exist?).to be_falsey
+        ArduinoCI::Host.symlink(__FILE__, new_path)
+        expect(ArduinoCI::Host.symlink?).to be_truthy
+        expect(ArduinoCI::Host.readlink.realpath).to eq(Pathname.new(__FILE__).realpath)
+      end
+    end
+  end
+
+end