forbid running fswatch in non-MacOS environment

lib/docker-sync/dependencies.rb

@@ -26,14 +26,16 @@ def self.ensure_all_for_mac!(config)
       Fswatch.ensure! if config.fswatch_required?
     end
 
-    def self.ensure_all_for_linux!(_config)
+    def self.ensure_all_for_linux!(config)
       Docker.ensure!
+      Fswatch.forbid! if config.fswatch_required?
     end
 
     def self.ensure_all_for_freebsd!(config)
       Docker.ensure!
       Unison.ensure!  if config.unison_required?
       Rsync.ensure!   if config.rsync_required?
+      Fswatch.forbid! if config.fswatch_required?
     end
   end
 end

lib/docker-sync/dependencies/fswatch.rb

@@ -1,8 +1,10 @@
 module DockerSync
   module Dependencies
     module Fswatch
+      UNSUPPORTED = 'Fswatch is not expected to run on platforms other then MacOS'
+
       def self.available?
-        raise 'Fswatch cannot be available for other platforms then MacOS' unless Environment.mac?
+        forbid! unless Environment.mac?
         return @available if defined? @available
         @available = find_executable0('fswatch')
       end
@@ -13,7 +15,11 @@ def self.ensure!
         PackageManager.install_package('fswatch')
         puts "please restart docker sync so the installation of fswatch takes effect"
         exit(1)
-    end
+      end
+
+      def self.forbid!
+        raise UNSUPPORTED
+      end
     end
   end
 end

spec/lib/docker-sync/dependencies_spec.rb

@@ -2,17 +2,20 @@
 
 RSpec.describe DockerSync::Dependencies do
   let(:config) { double(:config, unison_required?: false, rsync_required?: false, fswatch_required?: false) }
-  let(:linux?) { false }
-  let(:mac?)   { false }
+  let(:linux?)   { false }
+  let(:freebsd?) { false }
+  let(:mac?)     { false }
 
   before do
     allow(DockerSync::Environment).to receive(:linux?).and_return(linux?)
+    allow(DockerSync::Environment).to receive(:freebsd?).and_return(freebsd?)
     allow(DockerSync::Environment).to receive(:mac?).and_return(mac?)
   end
 
   describe '.ensure_all!(config)' do
     before do
       allow(described_class).to receive(:ensure_all_for_mac!)
+      allow(described_class).to receive(:ensure_all_for_freebsd!)
       allow(described_class).to receive(:ensure_all_for_linux!)
     end
 
@@ -30,12 +33,21 @@
     context 'when running on Linux' do
       let(:linux?) { true }
 
-      it 'delegates to `ensure_all_for_mac!` with given config' do
+      it 'delegates to `ensure_all_for_linux!` with given config' do
         subject
         expect(described_class).to have_received(:ensure_all_for_linux!).with(config)
       end
     end
 
+    context 'when running on FreeBSD' do
+      let(:freebsd?) { true }
+
+      it 'delegates to `ensure_all_for_freebsd!` with given config' do
+        subject
+        expect(described_class).to have_received(:ensure_all_for_freebsd!).with(config)
+      end
+    end
+
     context 'when running on another OS' do
       it 'raises an error' do
         expect { subject }.to raise_error(RuntimeError)
@@ -56,6 +68,41 @@
       subject
       expect(described_class::Docker).to have_received(:ensure!)
     end
+
+    context "when FSWatch is required by given `config`" do
+      before do
+        allow(config).to receive(:fswatch_required?).and_return(true)
+      end
+
+      it 'is forbidden' do
+        expect { subject }.to raise_error(DockerSync::Dependencies::Fswatch::UNSUPPORTED)
+      end
+    end
+  end
+
+  describe '.ensure_all_for_freebsd!(_config)' do
+    let(:freebsd?) { true }
+
+    before do
+      allow(described_class::Docker).to receive(:ensure!)
+    end
+
+    subject { described_class.ensure_all_for_freebsd!(config) }
+
+    it 'ensures that Docker is available' do
+      subject
+      expect(described_class::Docker).to have_received(:ensure!)
+    end
+
+    context "when FSWatch is required by given `config`" do
+      before do
+        allow(config).to receive(:fswatch_required?).and_return(true)
+      end
+
+      it 'is forbidden' do
+        expect { subject }.to raise_error(DockerSync::Dependencies::Fswatch::UNSUPPORTED)
+      end
+    end
   end
 
   describe '.ensure_all_for_mac!(config)' do