Add tests for runners execute route

Co-authored-by: Tobias Kantusch <tobias.kantusch@student.hpi.uni-potsdam.de>

runner/runner_test.go

@@ -1,6 +1,7 @@
 package runner
 
 import (
+	"context"
 	"encoding/json"
 	"github.com/stretchr/testify/assert"
 	"testing"
@@ -30,3 +31,29 @@ func TestMarshalRunner(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, "{\"runnerId\":\"42\",\"status\":\"ready\"}", string(marshal))
 }
+
+func TestNewContextReturnsNewContextWithRunner(t *testing.T) {
+	runner := NewExerciseRunner("testRunner")
+	ctx := context.Background()
+	newCtx := NewContext(ctx, runner)
+	storedRunner := newCtx.Value(runnerContextKey).(Runner)
+
+	assert.NotEqual(t, ctx, newCtx)
+	assert.Equal(t, runner, storedRunner)
+}
+
+func TestFromContextReturnsRunner(t *testing.T) {
+	runner := NewExerciseRunner("testRunner")
+	ctx := NewContext(context.Background(), runner)
+	storedRunner, ok := FromContext(ctx)
+
+	assert.True(t, ok)
+	assert.Equal(t, runner, storedRunner)
+}
+
+func TestFromContextReturnsIsNotOkWhenContextHasNoRunner(t *testing.T) {
+	ctx := context.Background()
+	_, ok := FromContext(ctx)
+
+	assert.False(t, ok)
+}