Check if plugin install provides specification

During a plugin install, if the plugin is already installed and
activated, no specification will be returned as there was nothing
new installed. In this situation, look for the requested plugin
within the activated specifications. If it is found, then proceed
since the plugin is installed. If it is not found, return an error.

lib/vagrant/bundler.rb

@@ -480,7 +480,7 @@ module Vagrant
         if update[:gems] == true || (update[:gems].respond_to?(:include?) && update[:gems].include?(name))
           if Gem::Requirement.new(gem_version).exact?
             gem_version = "> 0"
-            @logger.debug("Detected exact version match for `#{name}` plugin update. Reset to loose constraint #{gem_version.inspect}.")
+            @logger.debug("Detected exact version match for `#{name}` plugin update. Reset to loosen constraint #{gem_version.inspect}.")
           end
           skips << name
         end
@@ -565,10 +565,10 @@ module Vagrant
       activate_solution(solution)
 
       # Remove gems which are already installed
-      request_set.sorted_requests.delete_if do |activation_req|
-        rs_spec = activation_req.spec
-        if vagrant_internal_specs.detect{|ispec| ispec.name == rs_spec.name && ispec.version == rs_spec.version }
-          @logger.debug("Removing activation request from install. Already installed. (#{rs_spec.spec.full_name})")
+      request_set.sorted_requests.delete_if do |act_req|
+        rs = act_req.spec
+        if vagrant_internal_specs.detect{ |i| i.name == rs.name && i.version == rs.version }
+          @logger.debug("Removing activation request from install. Already installed. (#{rs.spec.full_name})")
           true
         end
       end

lib/vagrant/errors.rb

@@ -628,6 +628,10 @@ module Vagrant
       error_key(:plugin_install_license_not_found)
     end
 
+    class PluginInstallFailed < VagrantError
+      error_key(:plugin_install_failed)
+    end
+
     class PluginInstallSpace < VagrantError
       error_key(:plugin_install_space)
     end

lib/vagrant/plugin/manager.rb

@@ -150,17 +150,28 @@ module Vagrant
         else
           result = local_spec
         end
-        # Add the plugin to the state file
-        plugin_file = opts[:env_local] ? @local_file : @user_file
-        plugin_file.add_plugin(
-          result.name,
-          version: opts[:version],
-          require: opts[:require],
-          sources: opts[:sources],
-          env_local: !!opts[:env_local],
-          installed_gem_version: result.version.to_s
-        )
 
+        if result
+          # Add the plugin to the state file
+          plugin_file = opts[:env_local] ? @local_file : @user_file
+          plugin_file.add_plugin(
+            result.name,
+            version: opts[:version],
+            require: opts[:require],
+            sources: opts[:sources],
+            env_local: !!opts[:env_local],
+            installed_gem_version: result.version.to_s
+          )
+        else
+          r = Gem::Dependency.new(name, opts[:version])
+          result = Gem::Specification.find { |s|
+            s.satisfies_requirement?(r) &&
+              s.activated?
+          }
+          raise Errors::PluginInstallFailed,
+            name: name if result.nil?
+          @logger.warn("Plugin install returned no result as no new plugins were installed.")
+        end
         # After install clean plugin gems to remove any cruft. This is useful
         # for removing outdated dependencies or other versions of an installed
         # plugin if the plugin is upgraded/downgraded

templates/locales/en.yml

@@ -1130,6 +1130,10 @@ en:
         The license file to install could not be found. Please verify
         the path you gave is correct. The path to the license file given
         was: '%{path}'
+      plugin_install_failed: |-
+        Vagrant was unable to install the requested plugin: '%{name}'
+        Please try to install this plugin again. If Vagrant is still unable
+        to install the requested plugin, please report this error.
       plugin_install_space: |-
         The directory where plugins are installed (the Vagrant home directory)
         has a space in it. On Windows, there is a bug in Ruby when compiling

test/unit/vagrant/plugin/manager_test.rb

@@ -265,6 +265,25 @@ describe Vagrant::Plugin::Manager do
       expect(plugins["bar"]["gem_version"]).to eql("1.0")
     end
 
+    context "with existing activation" do
+      let(:value) { double("value") }
+
+      before do
+        expect(bundler).to receive(:install).and_return([])
+        allow(bundler).to receive(:clean)
+      end
+
+      it "should locate existing activation if available" do
+        expect(Gem::Specification).to receive(:find).and_return(value)
+        expect(subject.install_plugin("foo")).to eq(value)
+      end
+
+      it "should raise an error if no activation is located" do
+        expect(Gem::Specification).to receive(:find).and_return(nil)
+        expect { subject.install_plugin("foo") }.to raise_error(Vagrant::Errors::PluginInstallFailed)
+      end
+    end
+
     describe "installation options" do
       let(:specs) do
         specs = Array.new(5) { Gem::Specification.new }