chore: test cleanups (testcontainers#2608)

* Assert the error is what we expect

* Avoid panicking on c==nil case

* Add missing error handling

* Discard read bytes to not waste RAM

docker.go

@@ -3,7 +3,6 @@ package testcontainers
 import (
 	"archive/tar"
 	"bufio"
-	"bytes"
 	"context"
 	"encoding/base64"
 	"encoding/binary"
@@ -894,6 +893,9 @@ var _ ContainerProvider = (*DockerProvider)(nil)
 // BuildImage will build and image from context and Dockerfile, then return the tag
 func (p *DockerProvider) BuildImage(ctx context.Context, img ImageBuildInfo) (string, error) {
 	buildOptions, err := img.BuildOptions()
+	if err != nil {
+		return "", err
+	}
 
 	var buildError error
 	var resp types.ImageBuildResponse
@@ -925,8 +927,7 @@ func (p *DockerProvider) BuildImage(ctx context.Context, img ImageBuildInfo) (st
 
 	// need to read the response from Docker, I think otherwise the image
 	// might not finish building before continuing to execute here
-	buf := new(bytes.Buffer)
-	_, err = buf.ReadFrom(resp.Body)
+	_, err = io.Copy(io.Discard, resp.Body)
 	if err != nil {
 		return "", err
 	}

options_test.go

@@ -94,11 +94,14 @@ func TestWithLogConsumers(t *testing.T) {
 	c, err := testcontainers.GenericContainer(context.Background(), req)
 	// we expect an error because the MySQL environment variables are not set
 	// but this is expected because we just want to test the log consumer
-	require.Error(t, err)
-	defer func() {
-		err = c.Terminate(context.Background())
-		require.NoError(t, err)
-	}()
+	require.EqualError(t, err, "failed to start container: container exited with code 1")
+	// c might be not nil even on error
+	if c != nil {
+		defer func() {
+			err = c.Terminate(context.Background())
+			require.NoError(t, err)
+		}()
+	}
 
 	assert.NotEmpty(t, lc.msgs)
 }