diff --git a/spec/factories/runner.rb b/spec/factories/runner.rb
new file mode 100644
index 00000000..809d134e
--- /dev/null
+++ b/spec/factories/runner.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+# This factory does not request the runner management as the id is already provided.
+FactoryBot.define do
+  factory :runner do
+    runner_id { 'test-runner-id' }
+    association :execution_environment, factory: :ruby
+    association :user, factory: :external_user
+    waiting_time { 1.0 }
+  end
+end
diff --git a/spec/models/runner_spec.rb b/spec/models/runner_spec.rb
new file mode 100644
index 00000000..2c5c4b84
--- /dev/null
+++ b/spec/models/runner_spec.rb
@@ -0,0 +1,357 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe Runner do
+  let(:runner) { FactoryBot.create :runner }
+  let(:runner_id) { runner.runner_id }
+  let(:error_message) { 'test error message' }
+  let(:response_body) { nil }
+  let(:user) { FactoryBot.build :external_user }
+  let(:execution_environment) { FactoryBot.create :ruby }
+
+  # All requests handle a BadRequest (400) response the same way.
+  shared_examples 'BadRequest (400) error handling' do
+    let(:response_body) { {message: error_message}.to_json }
+    let(:response_status) { 400 }
+
+    it 'raises an error' do
+      expect { action.call }.to raise_error(Runner::Error::BadRequest, /#{error_message}/)
+    end
+  end
+
+  # All requests handle a Unauthorized (401) response the same way.
+  shared_examples 'Unauthorized (401) error handling' do
+    let(:response_status) { 401 }
+
+    it 'raises an error' do
+      expect { action.call }.to raise_error(Runner::Error::Unauthorized)
+    end
+  end
+
+  # All requests except creation and destruction handle a NotFound (404) response the same way.
+  shared_examples 'NotFound (404) error handling' do
+    let(:response_status) { 404 }
+
+    it 'raises an error' do
+      expect { action.call }.to raise_error(Runner::Error::NotFound, /Runner/)
+    end
+
+    it 'destroys the runner locally' do
+      expect { action.call }.to change(described_class, :count).by(-1)
+        .and raise_error(Runner::Error::NotFound)
+    end
+  end
+
+  # All requests handle an InternalServerError (500) response the same way.
+  shared_examples 'InternalServerError (500) error handling' do
+    shared_examples 'InternalServerError (500) with error code' do |error_code, error_class|
+      let(:response_status) { 500 }
+      let(:response_body) { {message: error_message, errorCode: error_code}.to_json }
+
+      it 'raises an error' do
+        expect { action.call }.to raise_error(error_class) do |error|
+          expect(error.message).to match(/#{error_message}/)
+          expect(error.message).to match(/#{error_code}/)
+        end
+      end
+    end
+
+    context 'when error code is nomad overload' do
+      include_examples(
+        'InternalServerError (500) with error code',
+        described_class.error_nomad_overload, Runner::Error::NotAvailable
+      )
+    end
+
+    context 'when error code is not nomad overload' do
+      include_examples(
+        'InternalServerError (500) with error code',
+        described_class.error_unknown, Runner::Error::InternalServerError
+      )
+    end
+  end
+
+  # All requests handle an unknown response status the same way.
+  shared_examples 'unknown response status error handling' do
+    let(:response_status) { 1337 }
+
+    it 'raises an error' do
+      expect { action.call }.to raise_error(Runner::Error::Unknown)
+    end
+  end
+
+  describe 'attribute validation' do
+    let(:runner) { FactoryBot.create :runner }
+
+    it 'validates the presence of the runner id' do
+      described_class.skip_callback(:validation, :before, :request_remotely)
+      runner.update(runner_id: nil)
+      expect(runner.errors[:runner_id]).to be_present
+      described_class.set_callback(:validation, :before, :request_remotely)
+    end
+
+    it 'validates the presence of an execution environment' do
+      runner.update(execution_environment: nil)
+      expect(runner.errors[:execution_environment]).to be_present
+    end
+
+    it 'validates the presence of a user' do
+      runner.update(user: nil)
+      expect(runner.errors[:user]).to be_present
+    end
+  end
+
+  describe 'creation' do
+    let(:action) { -> { described_class.create(user: user, execution_environment: execution_environment) } }
+    let!(:create_stub) do
+      WebMock
+        .stub_request(:post, "#{Runner::BASE_URL}/runners")
+        .with(
+          body: {executionEnvironmentId: execution_environment.id, inactivityTimeout: Runner::UNUSED_EXPIRATION_TIME},
+          headers: {'Content-Type' => 'application/json'}
+        )
+        .to_return(body: response_body, status: response_status)
+    end
+
+    context 'when a runner is created' do
+      let(:response_body) { {runnerId: runner_id}.to_json }
+      let(:response_status) { 200 }
+
+      it 'requests a runner from the runner management' do
+        action.call
+        expect(create_stub).to have_been_requested.once
+      end
+
+      it 'does not call the runner management again when updating' do
+        runner = action.call
+        runner.runner_id = 'another_id'
+        successfully_saved = runner.save
+        expect(successfully_saved).to be_truthy
+        expect(create_stub).to have_been_requested.once
+      end
+    end
+
+    context 'when the runner management returns Ok (200) with an id' do
+      let(:response_body) { {runnerId: runner_id}.to_json }
+      let(:response_status) { 200 }
+
+      it 'sets the runner id according to the response' do
+        runner = action.call
+        expect(runner.runner_id).to eq(runner_id)
+        expect(runner).to be_persisted
+      end
+    end
+
+    context 'when the runner management returns Ok (200) without an id' do
+      let(:response_body) { {}.to_json }
+      let(:response_status) { 200 }
+
+      it 'does not save the runner' do
+        runner = action.call
+        expect(runner).not_to be_persisted
+      end
+    end
+
+    context 'when the runner management returns Ok (200) with invalid JSON' do
+      let(:response_body) { '{hello}' }
+      let(:response_status) { 200 }
+
+      it 'raises an error' do
+        expect { action.call }.to raise_error(Runner::Error::Unknown)
+      end
+    end
+
+    context 'when the runner management returns BadRequest (400)' do
+      include_examples 'BadRequest (400) error handling'
+    end
+
+    context 'when the runner management returns Unauthorized (401)' do
+      include_examples 'Unauthorized (401) error handling'
+    end
+
+    context 'when the runner management returns NotFound (404)' do
+      let(:response_status) { 404 }
+
+      it 'raises an error' do
+        expect { action.call }.to raise_error(Runner::Error::NotFound, /Execution environment/)
+      end
+    end
+
+    context 'when the runner management returns InternalServerError (500)' do
+      include_examples 'InternalServerError (500) error handling'
+    end
+
+    context 'when the runner management returns an unknown response status' do
+      include_examples 'unknown response status error handling'
+    end
+  end
+
+  describe 'execute command' do
+    let(:command) { 'ls' }
+    let(:action) { -> { runner.execute_command(command) } }
+    let(:websocket_url) { 'ws://ws.example.com/path/to/websocket' }
+    let!(:execute_command_stub) do
+      WebMock
+        .stub_request(:post, "#{Runner::BASE_URL}/runners/#{runner_id}/execute")
+        .with(
+          body: {command: command, timeLimit: execution_environment.permitted_execution_time},
+          headers: {'Content-Type' => 'application/json'}
+        )
+        .to_return(body: response_body, status: response_status)
+    end
+
+    context 'when #execute_command is called' do
+      let(:response_status) { 200 }
+      let(:response_body) { {websocketUrl: websocket_url}.to_json }
+
+      it 'schedules an execution in the runner management' do
+        action.call
+        expect(execute_command_stub).to have_been_requested.once
+      end
+    end
+
+    context 'when the runner management returns Ok (200) with a websocket url' do
+      let(:response_status) { 200 }
+      let(:response_body) { {websocketUrl: websocket_url}.to_json }
+
+      it 'returns the url' do
+        url = action.call
+        expect(url).to eq(websocket_url)
+      end
+    end
+
+    context 'when the runner management returns Ok (200) without a websocket url' do
+      let(:response_body) { {}.to_json }
+      let(:response_status) { 200 }
+
+      it 'raises an error' do
+        expect { action.call }.to raise_error(Runner::Error::Unknown)
+      end
+    end
+
+    context 'when the runner management returns Ok (200) with invalid JSON' do
+      let(:response_body) { '{hello}' }
+      let(:response_status) { 200 }
+
+      it 'raises an error' do
+        expect { action.call }.to raise_error(Runner::Error::Unknown)
+      end
+    end
+
+    context 'when the runner management returns BadRequest (400)' do
+      include_examples 'BadRequest (400) error handling'
+    end
+
+    context 'when the runner management returns Unauthorized (401)' do
+      include_examples 'Unauthorized (401) error handling'
+    end
+
+    context 'when the runner management returns NotFound (404)' do
+      include_examples 'NotFound (404) error handling'
+    end
+
+    context 'when the runner management returns InternalServerError (500)' do
+      include_examples 'InternalServerError (500) error handling'
+    end
+
+    context 'when the runner management returns an unknown response status' do
+      include_examples 'unknown response status error handling'
+    end
+  end
+
+  describe 'destruction' do
+    let(:action) { -> { runner.destroy_remotely } }
+    let(:response_status) { 204 }
+    let!(:destroy_stub) do
+      WebMock
+        .stub_request(:delete, "#{Runner::BASE_URL}/runners/#{runner_id}")
+        .to_return(body: response_body, status: response_status)
+    end
+
+    it 'deletes the runner from the runner management' do
+      action.call
+      expect(destroy_stub).to have_been_requested.once
+    end
+
+    it 'does not destroy the runner locally' do
+      expect { action.call }.not_to change(described_class, :count)
+    end
+
+    context 'when the runner management returns NoContent (204)' do
+      it 'does not raise an error' do
+        expect { action.call }.not_to raise_error
+      end
+    end
+
+    context 'when the runner management returns Unauthorized (401)' do
+      include_examples 'Unauthorized (401) error handling'
+    end
+
+    context 'when the runner management returns NotFound (404)' do
+      let(:response_status) { 404 }
+
+      it 'raises an exception' do
+        expect { action.call }.to raise_error(Runner::Error::NotFound, /Runner/)
+      end
+    end
+
+    context 'when the runner management returns InternalServerError (500)' do
+      include_examples 'InternalServerError (500) error handling'
+    end
+
+    context 'when the runner management returns an unknown response status' do
+      include_examples 'unknown response status error handling'
+    end
+  end
+
+  describe 'copy files' do
+    let(:filename) { 'main.py' }
+    let(:file_content) { 'print("Hello World!")' }
+    let(:action) { -> { runner.copy_files({filename => file_content}) } }
+    let(:encoded_file_content) { Base64.strict_encode64(file_content) }
+    let(:response_status) { 204 }
+    let!(:copy_files_stub) do
+      WebMock
+        .stub_request(:patch, "#{Runner::BASE_URL}/runners/#{runner_id}/files")
+        .with(
+          body: {copy: [{path: filename, content: encoded_file_content}]},
+          headers: {'Content-Type' => 'application/json'}
+        )
+        .to_return(body: response_body, status: response_status)
+    end
+
+    it 'sends the files to the runner management' do
+      action.call
+      expect(copy_files_stub).to have_been_requested.once
+    end
+
+    context 'when the runner management returns NoContent (204)' do
+      let(:response_status) { 204 }
+
+      it 'does not raise an error' do
+        expect { action.call }.not_to raise_error
+      end
+    end
+
+    context 'when the runner management returns BadRequest (400)' do
+      include_examples 'BadRequest (400) error handling'
+    end
+
+    context 'when the runner management returns Unauthorized (401)' do
+      include_examples 'Unauthorized (401) error handling'
+    end
+
+    context 'when the runner management returns NotFound (404)' do
+      include_examples 'NotFound (404) error handling'
+    end
+
+    context 'when the runner management returns InternalServerError (500)' do
+      include_examples 'InternalServerError (500) error handling'
+    end
+
+    context 'when the runner management returns an unknown response status' do
+      include_examples 'unknown response status error handling'
+    end
+  end
+end