Detect and use (don't re-install) pre-existing Arduino libraries

Author: ianfixes

CHANGELOG.md

@@ -7,9 +7,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## [Unreleased]
 ### Added
 - Explicit checks that the requested test platforms are defined in YML
+- Method to guess whether a library is installed
 
 ### Changed
 - Refactored documentation
+- External libraries aren't forcibly installed via the Arduino binary (in `arduino_cmd_remote.rb`) if they appear to exist on disk already
 
 ### Deprecated
 

exe/arduino_ci_remote.rb

@@ -119,7 +119,11 @@ def assured_platform(purpose, name, config)
 end
 
 aux_libraries.each do |l|
-  assure("Installing aux library '#{l}'") { @arduino_cmd.install_library(l) }
+  if @arduino_cmd.library_present?(l)
+    assure("Using pre-existing library '#{l}'") { true }
+  else
+    assure("Installing aux library '#{l}'") { @arduino_cmd.install_library(l) }
+  end
 end
 
 # iterate boards / tests

lib/arduino_ci/arduino_cmd.rb

@@ -193,6 +193,17 @@ def library_path(library_name)
       File.join(_lib_dir, library_name)
     end
 
+    # Determine whether a library is present in the lib dir
+    #
+    # Note that `true` doesn't guarantee that the library is valid/installed
+    #  and `false` doesn't guarantee that the library isn't built-in
+    #
+    # @param library_name [String] The name of the library
+    # @return [bool]
+    def library_present?(library_name)
+      File.exist?(library_path(library_name))
+    end
+
     # update the library index
     # @return [bool] Whether the update succeeded
     def update_library_index

spec/arduino_cmd_spec.rb

@@ -46,6 +46,15 @@ def get_sketch(dir, file)
     end
   end
 
+  context "libraries" do
+    it "knows where to find libraries" do
+      fake_lib = "_____nope"
+      expected_dir = File.join(arduino_cmd._lib_dir, fake_lib)
+      expect(arduino_cmd.library_path(fake_lib)).to eq(expected_dir)
+      expect(arduino_cmd.library_present?(fake_lib)).to be false
+    end
+  end
+
   context "set_pref" do
 
     it "Sets key to what it was before" do