fix: nil pointer dereference in HealthStrategy (#802)

* [#801] Fix nil pointer dereference in HealthStrategy

* Added another test to prove HealthStrategy fails for nil Health

* Refactored error checking

* Update wait/health_test.go

Co-authored-by: Manuel de la Peña <social.mdelapenya@gmail.com>

* Update wait/health_test.go

Co-authored-by: Manuel de la Peña <social.mdelapenya@gmail.com>

* Update wait/health_test.go

Co-authored-by: Manuel de la Peña <social.mdelapenya@gmail.com>

---------

Co-authored-by: Manuel de la Peña <social.mdelapenya@gmail.com>

wait/health.go

@@ -2,6 +2,7 @@ package wait
 
 import (
 	"context"
+	"github.com/docker/docker/api/types"
 	"time"
 )
 
@@ -76,7 +77,7 @@ func (ws *HealthStrategy) WaitUntilReady(ctx context.Context, target StrategyTar
 			if err != nil {
 				return err
 			}
-			if state.Health.Status != "healthy" {
+			if state.Health == nil || state.Health.Status != types.Healthy {
 				time.Sleep(ws.PollInterval)
 				continue
 			}

wait/health_test.go

@@ -0,0 +1,93 @@
+package wait
+
+import (
+	"context"
+	"errors"
+	"github.com/stretchr/testify/assert"
+	"io"
+	"testing"
+	"time"
+
+	"github.com/docker/docker/api/types"
+	"github.com/docker/go-connections/nat"
+	tcexec "github.com/testcontainers/testcontainers-go/exec"
+)
+
+type healthStrategyTarget struct {
+	Health *types.Health
+}
+
+func (st healthStrategyTarget) Host(ctx context.Context) (string, error) {
+	return "", nil
+}
+
+func (st healthStrategyTarget) Ports(ctx context.Context) (nat.PortMap, error) {
+	return nil, nil
+}
+
+func (st healthStrategyTarget) MappedPort(ctx context.Context, n nat.Port) (nat.Port, error) {
+	return n, nil
+}
+
+func (st healthStrategyTarget) Logs(ctx context.Context) (io.ReadCloser, error) {
+	return nil, nil
+}
+
+func (st healthStrategyTarget) Exec(ctx context.Context, cmd []string, options ...tcexec.ProcessOption) (int, io.Reader, error) {
+	return 0, nil, nil
+}
+
+func (st healthStrategyTarget) State(ctx context.Context) (*types.ContainerState, error) {
+	return &types.ContainerState{Health: st.Health}, nil
+}
+
+// TestWaitForHealthTimesOutForUnhealthy confirms that an unhealthy container will eventually
+// time out.
+func TestWaitForHealthTimesOutForUnhealthy(t *testing.T) {
+	target := healthStrategyTarget{Health: &types.Health{Status: types.Unhealthy}}
+	wg := NewHealthStrategy().WithStartupTimeout(100 * time.Millisecond)
+	err := wg.WaitUntilReady(context.Background(), target)
+
+	assert.NotNil(t, err)
+	assert.True(t, errors.Is(err, context.DeadlineExceeded))
+}
+
+// TestWaitForHealthSucceeds ensures that a healthy container always succeeds.
+func TestWaitForHealthSucceeds(t *testing.T) {
+	target := healthStrategyTarget{Health: &types.Health{Status: types.Healthy}}
+	wg := NewHealthStrategy().WithStartupTimeout(100 * time.Millisecond)
+	err := wg.WaitUntilReady(context.Background(), target)
+
+	assert.Nil(t, err)
+}
+
+// TestWaitForHealthWithNil checks that an initial `nil` Health will not casue a panic,
+// and if the container eventually becomes healthy, the HealthStrategy will succeed.
+func TestWaitForHealthWithNil(t *testing.T) {
+	target := &healthStrategyTarget{Health: nil}
+	wg := NewHealthStrategy().
+		WithStartupTimeout(500 * time.Millisecond).
+		WithPollInterval(100 * time.Millisecond)
+
+	go func(target *healthStrategyTarget) {
+		// wait a bit to simulate startup time and give check time to at least
+		// try a few times with a nil Health
+		time.Sleep(200 * time.Millisecond)
+		target.Health = &types.Health{Status: types.Healthy}
+	}(target)
+
+	err := wg.WaitUntilReady(context.Background(), target)
+	assert.Nil(t, err)
+}
+
+// TestWaitFailsForNilHealth checks that Health always nil fails (but will NOT cause a panic)
+func TestWaitFailsForNilHealth(t *testing.T) {
+	target := &healthStrategyTarget{Health: nil}
+	wg := NewHealthStrategy().
+		WithStartupTimeout(500 * time.Millisecond).
+		WithPollInterval(100 * time.Millisecond)
+
+	err := wg.WaitUntilReady(context.Background(), target)
+	assert.NotNil(t, err)
+	assert.True(t, errors.Is(err, context.DeadlineExceeded))
+}