Isolates testify to one file, so that it is easier to remove (#460)

This starts the process of removing all dependencies from wazero, by
isolating all assertions we use into a single file. This allows us to
port those assertions as we have time, and when twitchy is gone, the
project literally has no dependencies except go!

Signed-off-by: Adrian Cole <adrian@tetrate.io>

internal/testing/require/require.go

@@ -0,0 +1,102 @@
+// Package require includes test assertions that fail the test immediately. This is like to testify, but without a
+// dependency.
+//
+// Note: Assertions here are internal and are free to be customized to only support valid WebAssembly types, or to
+// reduce code in tests that only require certain types.
+package require
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// TODO: implement, test and document each function without using testify
+
+func Contains(t *testing.T, s interface{}, contains interface{}, msgAndArgs ...interface{}) {
+	require.Contains(t, s, contains, msgAndArgs)
+}
+
+func Empty(t *testing.T, object interface{}, msgAndArgs ...interface{}) {
+	require.Empty(t, object, msgAndArgs)
+}
+
+func Equal(t *testing.T, expected interface{}, actual interface{}, msgAndArgs ...interface{}) {
+	require.Equal(t, expected, actual, msgAndArgs)
+}
+
+func EqualError(t *testing.T, theError error, errString string, msgAndArgs ...interface{}) {
+	require.EqualError(t, theError, errString, msgAndArgs)
+}
+
+func Error(t *testing.T, err error, msgAndArgs ...interface{}) {
+	require.Error(t, err, msgAndArgs)
+}
+
+func ErrorIs(t *testing.T, err error, target error, msgAndArgs ...interface{}) {
+	require.ErrorIs(t, err, target, msgAndArgs)
+}
+
+func False(t *testing.T, value bool, msgAndArgs ...interface{}) {
+	require.False(t, value, msgAndArgs)
+}
+
+func Len(t *testing.T, object interface{}, length int, msgAndArgs ...interface{}) {
+	require.Len(t, object, length, msgAndArgs)
+}
+
+func Nil(t *testing.T, object interface{}, msgAndArgs ...interface{}) {
+	require.Nil(t, object, msgAndArgs)
+}
+
+func NoError(t *testing.T, err error, msgAndArgs ...interface{}) {
+	require.NoError(t, err, msgAndArgs)
+}
+
+func NotContains(t *testing.T, s interface{}, contains interface{}, msgAndArgs ...interface{}) {
+	require.NotContains(t, s, contains, msgAndArgs)
+}
+
+func NotEmpty(t *testing.T, object interface{}, msgAndArgs ...interface{}) {
+	require.NotEmpty(t, object, msgAndArgs)
+}
+
+func NotEqual(t *testing.T, expected interface{}, actual interface{}, msgAndArgs ...interface{}) {
+	require.NotEqual(t, expected, actual, msgAndArgs)
+}
+
+func NotNil(t *testing.T, object interface{}, msgAndArgs ...interface{}) {
+	require.NotNil(t, object, msgAndArgs)
+}
+
+func NotSame(t *testing.T, expected interface{}, actual interface{}, msgAndArgs ...interface{}) {
+	require.NotSame(t, expected, actual, msgAndArgs)
+}
+
+// CapturePanic returns an error recovered from a panic. If the panic was not an error, this converts it to one.
+func CapturePanic(panics func()) (err error) {
+	defer func() {
+		if recovered := recover(); recovered != nil {
+			if e, ok := recovered.(error); ok {
+				err = e
+			} else {
+				err = fmt.Errorf("%v", recovered)
+			}
+		}
+	}()
+	panics()
+	return
+}
+
+func Same(t *testing.T, expected interface{}, actual interface{}, msgAndArgs ...interface{}) {
+	require.Same(t, expected, actual, msgAndArgs)
+}
+
+func True(t *testing.T, value bool, msgAndArgs ...interface{}) {
+	require.True(t, value, msgAndArgs)
+}
+
+func Zero(t *testing.T, i interface{}, msgAndArgs ...interface{}) {
+	require.Zero(t, i, msgAndArgs)
+}