diff --git a/tests/constants.go b/tests/constants.go
index 9cfb01f..ce7b617 100644
--- a/tests/constants.go
+++ b/tests/constants.go
@@ -11,6 +11,7 @@ const (
 	DefaultEnvironmentIdAsInteger = 0
 	DefaultEnvironmentIdAsString  = "0"
 	AnotherEnvironmentIdAsInteger = 42
+	AnotherEnvironmentIdAsString  = "42"
 	DefaultJobId                  = "s0m3-j0b-1d"
 	AnotherJobId                  = "4n0th3r-j0b-1d"
 	DefaultRunnerId               = "s0m3-r4nd0m-1d"
diff --git a/tests/e2e/e2e_test.go b/tests/e2e/e2e_test.go
index fe5dbb0..9d8706e 100644
--- a/tests/e2e/e2e_test.go
+++ b/tests/e2e/e2e_test.go
@@ -1,6 +1,7 @@
 package e2e
 
 import (
+	nomadApi "github.com/hashicorp/nomad/api"
 	"github.com/stretchr/testify/suite"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/config"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/logging"
@@ -15,7 +16,11 @@ import (
 * For the e2e tests a nomad cluster must be connected and poseidon must be running.
  */
 
-var log = logging.GetLogger("e2e")
+var (
+	log            = logging.GetLogger("e2e")
+	nomadClient    *nomadApi.Client
+	nomadNamespace string
+)
 
 type E2ETestSuite struct {
 	suite.Suite
@@ -35,7 +40,16 @@ func TestMain(m *testing.M) {
 	log.Info("Test Setup")
 	err := config.InitConfig()
 	if err != nil {
-		log.Warn("Could not initialize configuration")
+		log.WithError(err).Fatal("Could not initialize configuration")
+	}
+	nomadNamespace = config.Config.Nomad.Namespace
+	nomadClient, err = nomadApi.NewClient(&nomadApi.Config{
+		Address:   config.Config.NomadAPIURL().String(),
+		TLSConfig: &nomadApi.TLSConfig{},
+		Namespace: nomadNamespace,
+	})
+	if err != nil {
+		log.WithError(err).Fatal("Could not create Nomad client")
 	}
 	// ToDo: Add Nomad job here when it is possible to create execution environments. See #26.
 	log.Info("Test Run")
diff --git a/tests/e2e/environments_test.go b/tests/e2e/environments_test.go
new file mode 100644
index 0000000..15ea725
--- /dev/null
+++ b/tests/e2e/environments_test.go
@@ -0,0 +1,143 @@
+package e2e
+
+import (
+	nomadApi "github.com/hashicorp/nomad/api"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/api"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/api/dto"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/tests"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/tests/helpers"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+const (
+	dockerImage = "python:latest"
+)
+
+func TestCreateOrUpdateEnvironment(t *testing.T) {
+	path := helpers.BuildURL(api.BasePath, api.EnvironmentsPath, tests.AnotherEnvironmentIdAsString)
+
+	t.Run("returns bad request with empty body", func(t *testing.T) {
+		resp, err := helpers.HttpPut(path, strings.NewReader(""))
+		require.Nil(t, err)
+		assert.Equal(t, http.StatusBadRequest, resp.StatusCode)
+
+		_ = resp.Body.Close()
+	})
+
+	request := dto.ExecutionEnvironmentRequest{
+		PrewarmingPoolSize: 1,
+		CPULimit:           100,
+		MemoryLimit:        100,
+		Image:              dockerImage,
+		NetworkAccess:      false,
+		ExposedPorts:       nil,
+	}
+
+	t.Run("creates correct environment in Nomad", func(t *testing.T) {
+		assertPutReturnsStatusAndZeroContent(t, path, request, http.StatusCreated)
+		validateJob(t, request)
+	})
+
+	t.Run("updates limits in Nomad correctly", func(t *testing.T) {
+		updateRequest := request
+		updateRequest.CPULimit = 1337
+		updateRequest.MemoryLimit = 142
+
+		assertPutReturnsStatusAndZeroContent(t, path, updateRequest, http.StatusNoContent)
+		validateJob(t, updateRequest)
+	})
+
+	t.Run("adds network correctly", func(t *testing.T) {
+		updateRequest := request
+		updateRequest.NetworkAccess = true
+		updateRequest.ExposedPorts = []uint16{42, 1337}
+
+		assertPutReturnsStatusAndZeroContent(t, path, updateRequest, http.StatusNoContent)
+		validateJob(t, updateRequest)
+	})
+
+	t.Run("removes network correctly", func(t *testing.T) {
+		require.False(t, request.NetworkAccess)
+		require.Nil(t, request.ExposedPorts)
+		assertPutReturnsStatusAndZeroContent(t, path, request, http.StatusNoContent)
+		validateJob(t, request)
+	})
+
+	_, _, err := nomadClient.Jobs().DeregisterOpts(
+		tests.AnotherEnvironmentIdAsString, &nomadApi.DeregisterOptions{Purge: true}, nil)
+	if err != nil {
+		t.Fatalf("Error when removing test job %v", err)
+	}
+}
+
+func assertPutReturnsStatusAndZeroContent(t *testing.T, path string,
+	request dto.ExecutionEnvironmentRequest, status int) {
+	t.Helper()
+	resp, err := helpers.HttpPutJSON(path, request)
+	require.Nil(t, err)
+	assert.Equal(t, status, resp.StatusCode)
+	assert.Equal(t, int64(0), resp.ContentLength)
+
+	_ = resp.Body.Close()
+}
+
+func validateJob(t *testing.T, expected dto.ExecutionEnvironmentRequest) {
+	t.Helper()
+	job := findNomadJob(t, tests.AnotherEnvironmentIdAsString)
+
+	assertEqualValueStringPointer(t, nomadNamespace, job.Namespace)
+	assertEqualValueStringPointer(t, "batch", job.Type)
+	require.Equal(t, 1, len(job.TaskGroups))
+
+	taskGroup := job.TaskGroups[0]
+	require.NotNil(t, taskGroup.Count)
+	// Poseidon might have already scaled the registered job up once.
+	prewarmingPoolSizeInt := int(expected.PrewarmingPoolSize)
+	taskGroupCount := *taskGroup.Count
+	assert.True(t, prewarmingPoolSizeInt == taskGroupCount || prewarmingPoolSizeInt+1 == taskGroupCount)
+	assertEqualValueIntPointer(t, int(expected.PrewarmingPoolSize), taskGroup.Count)
+	require.Equal(t, 1, len(taskGroup.Tasks))
+
+	task := taskGroup.Tasks[0]
+	assertEqualValueIntPointer(t, int(expected.CPULimit), task.Resources.CPU)
+	assertEqualValueIntPointer(t, int(expected.MemoryLimit), task.Resources.MemoryMB)
+	assert.Equal(t, expected.Image, task.Config["image"])
+
+	if expected.NetworkAccess {
+		assert.Equal(t, "", task.Config["network_mode"])
+		require.Equal(t, 1, len(taskGroup.Networks))
+		network := taskGroup.Networks[0]
+		assert.Equal(t, len(expected.ExposedPorts), len(network.DynamicPorts))
+		for _, port := range network.DynamicPorts {
+			assert.Contains(t, expected.ExposedPorts, uint16(port.To))
+		}
+	} else {
+		assert.Equal(t, "none", task.Config["network_mode"])
+		assert.Equal(t, 0, len(taskGroup.Networks))
+	}
+}
+
+func findNomadJob(t *testing.T, jobID string) *nomadApi.Job {
+	t.Helper()
+	job, _, err := nomadClient.Jobs().Info(jobID, nil)
+	if err != nil {
+		t.Fatalf("Error retrieving Nomad job: %v", err)
+	}
+	return job
+}
+
+func assertEqualValueStringPointer(t *testing.T, value string, valueP *string) {
+	t.Helper()
+	require.NotNil(t, valueP)
+	assert.Equal(t, value, *valueP)
+}
+
+func assertEqualValueIntPointer(t *testing.T, value int, valueP *int) {
+	t.Helper()
+	require.NotNil(t, valueP)
+	assert.Equal(t, value, *valueP)
+}
diff --git a/tests/helpers/test_helpers.go b/tests/helpers/test_helpers.go
index 1c046de..f5197a4 100644
--- a/tests/helpers/test_helpers.go
+++ b/tests/helpers/test_helpers.go
@@ -149,3 +149,18 @@ func HttpPatch(url string, contentType string, body io.Reader) (response *http.R
 	client := &http.Client{}
 	return client.Do(req)
 }
+
+func HttpPut(url string, body io.Reader) (response *http.Response, err error) {
+	req, _ := http.NewRequest(http.MethodPut, url, body)
+	client := &http.Client{}
+	return client.Do(req)
+}
+
+func HttpPutJSON(url string, body interface{}) (response *http.Response, err error) {
+	requestString, err := json.Marshal(body)
+	if err != nil {
+		return
+	}
+	reader := strings.NewReader(string(requestString))
+	return HttpPut(url, reader)
+}