You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: getters_test.go
    path of file: ./repos/chainlink/core/services/pipeline
    
    the code of the file until where you have to start completion: package pipeline_test

import (
	"math/big"
	"testing"

	"github.com/pkg/errors"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"github.com/smartcontractkit/chainlink/v2/core/services/pipeline"
)

func TestGetters_VarExpr(t *testing.T) {
	t.Parallel()

	vars := createTestVars()

	tests := []struct {
		expr   string
		result interface{}
		err    error
	}{
		// no errors
		{"$(foo.bar)", "value", nil},
		{" $(foo.bar)", "value", nil},
		{"$(foo.bar) ", "value", nil},
		{"$( foo.bar)", "value", nil},
		{"$(foo.bar 
    
func TestGetters_VarExpr(t *testing.T) {
	t.Parallel()

	vars := createTestVars()

	tests := []struct {
		expr   string
		result interface{}
		err    error
	}{
		// no errors
		{"$(foo.bar)", "value", nil},
		{" $(foo.bar)", "value", nil},
		{"$(foo.bar) ", "value", nil},
		{"$( foo.bar)", "value", nil},
		{"$(foo.bar )", "value", nil},
		{"$( foo.bar )", "value", nil},
		{" $( foo.bar )", "value", nil},
		// errors
		{"  ", nil, pipeline.ErrParameterEmpty},
		{"$()", nil, pipeline.ErrParameterEmpty},
		{"$", nil, pipeline.ErrParameterEmpty},
		{"$(", nil, pipeline.ErrParameterEmpty},
		{"$)", nil, pipeline.ErrParameterEmpty},
		{"()", nil, pipeline.ErrParameterEmpty},
		{"$(foo.bar", nil, pipeline.ErrParameterEmpty},
		{"$foo.bar)", nil, pipeline.ErrParameterEmpty},
		{"(foo.bar)", nil, pipeline.ErrParameterEmpty},
		{"foo.bar", nil, pipeline.ErrParameterEmpty},
		{"$(err)", nil, pipeline.ErrTooManyErrors},
	}

	for _, test := range tests {
		t.Run(test.expr, func(t *testing.T) {
			getter := pipeline.VarExpr(test.expr, vars)
			v, err := getter()
			if test.err == nil {
				assert.NoError(t, err)
				assert.Equal(t, test.result, v)
			} else {
				assert.Equal(t, test.err, errors.Cause(err))
			}
		})
	}
}