Move NullReader from nomad to util package.

nomad/nomad.go

@@ -8,6 +8,7 @@ import (
 	"github.com/hashicorp/nomad/nomad/structs"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/config"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/logging"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/util"
 	"io"
 	"net/url"
 	"time"
@@ -287,15 +288,6 @@ func (a *APIClient) LoadEnvironmentJobs() ([]*nomadApi.Job, error) {
 	return jobs, nil
 }
 
-// nullReader is a struct that implements the io.Reader interface and returns nothing when reading
-// from it.
-type nullReader struct{}
-
-func (r nullReader) Read(_ []byte) (int, error) {
-	// An empty select blocks forever.
-	select {}
-}
-
 // ExecuteCommand executes the given command in the given allocation.
 // If tty is true, Nomad would normally write stdout and stderr of the command
 // both on the stdout stream. However, if the InteractiveStderr server config option is true,
@@ -328,7 +320,7 @@ func (a *APIClient) executeCommandInteractivelyWithStderr(allocationID string, c
 	stderrExitChan := make(chan int)
 	go func() {
 		// Catch stderr in separate execution.
-		exit, err := a.Execute(allocationID, ctx, stderrFifoCommand(currentNanoTime), true, nullReader{}, stderr, io.Discard)
+		exit, err := a.Execute(allocationID, ctx, stderrFifoCommand(currentNanoTime), true, util.NullReader{}, stderr, io.Discard)
 		if err != nil {
 			log.WithError(err).WithField("runner", allocationID).Warn("Stderr task finished with error")
 		}

nomad/nomad_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/stretchr/testify/suite"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/config"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/tests"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/util"
 	"io"
 	"net/url"
 	"regexp"
@@ -673,7 +674,7 @@ func (s *ExecuteCommandTestSuite) TestWithSeparateStderr() {
 	})
 
 	exitCode, err := s.nomadAPIClient.
-		ExecuteCommand(s.allocationID, s.ctx, s.testCommandArray, withTTY, nullReader{}, &stdout, &stderr)
+		ExecuteCommand(s.allocationID, s.ctx, s.testCommandArray, withTTY, util.NullReader{}, &stdout, &stderr)
 	s.Require().NoError(err)
 
 	s.apiMock.AssertNumberOfCalls(s.T(), "Execute", 2)
@@ -704,7 +705,7 @@ func (s *ExecuteCommandTestSuite) TestWithSeparateStderrReturnsCommandError() {
 	s.mockExecute(s.testCommandArray, 1, tests.ErrDefault, func(args mock.Arguments) {})
 	s.mockExecute(mock.AnythingOfType("[]string"), 1, nil, func(args mock.Arguments) {})
 	_, err := s.nomadAPIClient.
-		ExecuteCommand(s.allocationID, s.ctx, s.testCommandArray, withTTY, nullReader{}, io.Discard, io.Discard)
+		ExecuteCommand(s.allocationID, s.ctx, s.testCommandArray, withTTY, util.NullReader{}, io.Discard, io.Discard)
 	s.Equal(tests.ErrDefault, err)
 }
 
@@ -726,7 +727,7 @@ func (s *ExecuteCommandTestSuite) TestWithoutSeparateStderr() {
 	})
 
 	exitCode, err := s.nomadAPIClient.
-		ExecuteCommand(s.allocationID, s.ctx, s.testCommandArray, withTTY, nullReader{}, &stdout, &stderr)
+		ExecuteCommand(s.allocationID, s.ctx, s.testCommandArray, withTTY, util.NullReader{}, &stdout, &stderr)
 	s.Require().NoError(err)
 
 	s.apiMock.AssertNumberOfCalls(s.T(), "Execute", 1)
@@ -739,7 +740,7 @@ func (s *ExecuteCommandTestSuite) TestWithoutSeparateStderrReturnsCommandError()
 	config.Config.Server.InteractiveStderr = false
 	s.mockExecute(s.testCommandArray, 1, tests.ErrDefault, func(args mock.Arguments) {})
 	_, err := s.nomadAPIClient.
-		ExecuteCommand(s.allocationID, s.ctx, s.testCommandArray, withTTY, nullReader{}, io.Discard, io.Discard)
+		ExecuteCommand(s.allocationID, s.ctx, s.testCommandArray, withTTY, util.NullReader{}, io.Discard, io.Discard)
 	s.Equal(tests.ErrDefault, err)
 }
 
@@ -750,14 +751,3 @@ func (s *ExecuteCommandTestSuite) mockExecute(command interface{}, exitCode int,
 		Run(runFunc).
 		Return(exitCode, err)
 }
-
-func TestNullReaderDoesNotReturnImmediately(t *testing.T) {
-	reader := &nullReader{}
-	readerReturned := make(chan bool)
-	go func() {
-		p := make([]byte, 5)
-		_, _ = reader.Read(p)
-		close(readerReturned)
-	}()
-	assert.False(t, tests.ChannelReceivesSomething(readerReturned, tests.ShortTimeout))
-}

util/util.go

@@ -0,0 +1,10 @@
+package util
+
+// NullReader is a struct that implements the io.Reader interface and returns nothing when reading
+// from it.
+type NullReader struct{}
+
+func (r NullReader) Read(_ []byte) (int, error) {
+	// An empty select blocks forever.
+	select {}
+}

util/util_test.go

@@ -0,0 +1,18 @@
+package util
+
+import (
+	"github.com/stretchr/testify/assert"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/tests"
+	"testing"
+)
+
+func TestNullReaderDoesNotReturnImmediately(t *testing.T) {
+	reader := &NullReader{}
+	readerReturned := make(chan bool)
+	go func() {
+		p := make([]byte, 5)
+		_, _ = reader.Read(p)
+		close(readerReturned)
+	}()
+	assert.False(t, tests.ChannelReceivesSomething(readerReturned, tests.ShortTimeout))
+}