implemented pooling for Docker containers

spec/models/execution_environment_spec.rb

@@ -4,10 +4,9 @@ describe ExecutionEnvironment do
   let(:execution_environment) { ExecutionEnvironment.create }
 
   it 'validates that the Docker image works', docker: true do
-    expect(execution_environment).to receive(:working_docker_image?).and_call_original
     expect(execution_environment).to receive(:validate_docker_image?).and_return(true)
-    execution_environment.update(docker_image: 'invalid')
-    expect(execution_environment.errors[:docker_image]).to be_present
+    expect(execution_environment).to receive(:working_docker_image?)
+    execution_environment.update(docker_image: FactoryGirl.attributes_for(:ruby)[:docker_image])
   end
 
   it 'validates the presence of a Docker image name' do
@@ -18,15 +17,26 @@ describe ExecutionEnvironment do
     expect(execution_environment.errors[:name]).to be_present
   end
 
-  it 'validates the numericality of a permitted run time' do
+  it 'validates the numericality of the permitted run time' do
     execution_environment.update(permitted_execution_time: Math::PI)
     expect(execution_environment.errors[:permitted_execution_time]).to be_present
   end
 
   it 'validates the presence of a permitted run time' do
+    execution_environment.update(permitted_execution_time: nil)
     expect(execution_environment.errors[:permitted_execution_time]).to be_present
   end
 
+  it 'validates the numericality of the pool size' do
+    execution_environment.update(pool_size: Math::PI)
+    expect(execution_environment.errors[:pool_size]).to be_present
+  end
+
+  it 'validates the presence of a pool size' do
+    execution_environment.update(pool_size: nil)
+    expect(execution_environment.errors[:pool_size]).to be_present
+  end
+
   it 'validates the presence of a run command' do
     expect(execution_environment.errors[:run_command]).to be_present
   end
@@ -38,39 +48,40 @@ describe ExecutionEnvironment do
 
   describe '#validate_docker_image?' do
     it 'is false in the test environment' do
+      expect(Rails.env.test?).to be true
       expect(execution_environment.send(:validate_docker_image?)).to be false
     end
 
     it 'is false without a Docker image' do
-      allow(Rails).to receive(:env).and_return('production')
+      expect(execution_environment.docker_image).to be_blank
       expect(execution_environment.send(:validate_docker_image?)).to be false
     end
 
     it 'is true otherwise' do
-      execution_environment.docker_image = DockerClient.image_tags.first
-      expect(Rails).to receive(:env).and_return('production')
+      execution_environment.docker_image = FactoryGirl.attributes_for(:ruby)[:docker_image]
+      allow(Rails.env).to receive(:test?).and_return(false)
       expect(execution_environment.send(:validate_docker_image?)).to be true
     end
   end
 
   describe '#working_docker_image?', docker: true do
     let(:working_docker_image?) { execution_environment.send(:working_docker_image?) }
-    before(:each) { expect_any_instance_of(DockerClient).to receive(:find_image_by_tag).and_return(Object.new) }
+    before(:each) { expect(DockerClient).to receive(:find_image_by_tag).and_return(Object.new) }
 
     it 'instantiates a Docker client' do
       expect(DockerClient).to receive(:new).with(execution_environment: execution_environment).and_call_original
-      expect_any_instance_of(DockerClient).to receive(:execute_command).and_return({})
+      expect_any_instance_of(DockerClient).to receive(:execute_arbitrary_command).and_return({})
       working_docker_image?
     end
 
     it 'executes the validation command' do
-      expect_any_instance_of(DockerClient).to receive(:execute_command).with(ExecutionEnvironment::VALIDATION_COMMAND).and_return({})
+      expect_any_instance_of(DockerClient).to receive(:execute_arbitrary_command).with(ExecutionEnvironment::VALIDATION_COMMAND).and_return({})
       working_docker_image?
     end
 
     context 'when the command produces an error' do
       it 'adds an error' do
-        expect_any_instance_of(DockerClient).to receive(:execute_command).and_return({stderr: 'command not found'})
+        expect_any_instance_of(DockerClient).to receive(:execute_arbitrary_command).and_return({stderr: 'command not found'})
         working_docker_image?
         expect(execution_environment.errors[:docker_image]).to be_present
       end
@@ -78,7 +89,7 @@ describe ExecutionEnvironment do
 
     context 'when the Docker client produces an error' do
       it 'adds an error' do
-        expect_any_instance_of(DockerClient).to receive(:execute_command).and_raise(DockerClient::Error)
+        expect_any_instance_of(DockerClient).to receive(:execute_arbitrary_command).and_raise(DockerClient::Error)
         working_docker_image?
         expect(execution_environment.errors[:docker_image]).to be_present
       end