Implement MergeContext

that has multiple contexts as parent and chooses the earliest deadline.

pkg/util/merge_context_test.go

@@ -0,0 +1,69 @@
+package util
+
+import (
+	"context"
+	"github.com/openHPI/poseidon/pkg/dto"
+	"github.com/openHPI/poseidon/tests"
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"time"
+)
+
+func TestMergeContext_Deadline(t *testing.T) {
+	ctxWithoutDeadline := context.Background()
+	earlyDeadline := time.Now().Add(time.Second)
+	ctxWithEarlyDeadline, cancel := context.WithDeadline(context.Background(), earlyDeadline)
+	defer cancel()
+	ctxWithLateDeadline, cancel := context.WithDeadline(context.Background(), time.Now().Add(time.Hour))
+	defer cancel()
+
+	ctx := NewMergeContext([]context.Context{ctxWithoutDeadline, ctxWithEarlyDeadline, ctxWithLateDeadline})
+	deadline, ok := ctx.Deadline()
+
+	assert.True(t, ok)
+	assert.Equal(t, earlyDeadline, deadline, "The ealiest deadline is returned")
+}
+
+func TestMergeContext_Done(t *testing.T) {
+	ctxWithoutDeadline := context.Background()
+	ctxWithEarlyDeadline, cancel := context.WithTimeout(context.Background(), 2*tests.ShortTimeout)
+	defer cancel()
+	ctxWithLateDeadline, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+
+	ctx := NewMergeContext([]context.Context{ctxWithoutDeadline, ctxWithEarlyDeadline, ctxWithLateDeadline})
+
+	select {
+	case <-ctx.Done():
+		assert.Fail(t, "mergeContext is done before any of its parents")
+		return
+	case <-time.After(tests.ShortTimeout):
+	}
+
+	select {
+	case <-ctx.Done():
+	case <-time.After(3 * tests.ShortTimeout):
+		assert.Fail(t, "mergeContext is not done after the earliest of its parents")
+		return
+	}
+}
+
+func TestMergeContext_Err(t *testing.T) {
+	ctxWithoutDeadline := context.Background()
+	ctxCancelled, cancel := context.WithCancel(context.Background())
+	ctx := NewMergeContext([]context.Context{ctxWithoutDeadline, ctxCancelled})
+
+	assert.NoError(t, ctx.Err())
+	cancel()
+	assert.Error(t, ctx.Err())
+}
+
+func TestMergeContext_Value(t *testing.T) {
+	ctxWithAValue := context.WithValue(context.Background(), dto.ContextKey("keyA"), "valueA")
+	ctxWithAnotherValue := context.WithValue(context.Background(), dto.ContextKey("keyB"), "valueB")
+	ctx := NewMergeContext([]context.Context{ctxWithAValue, ctxWithAnotherValue})
+
+	assert.Equal(t, "valueA", ctx.Value(dto.ContextKey("keyA")))
+	assert.Equal(t, "valueB", ctx.Value(dto.ContextKey("keyB")))
+	assert.Nil(t, ctx.Value("keyC"))
+}