step_rapid_test.go

package main

import (
	"log"
	"os"
	"path/filepath"
	"testing"

	"pgregory.net/rapid"
)

// TestReadAndWriteTrace uses rapid to do property based testing
// of reading and writing traces.
// It generates a random trace, writes it to a file, then reads it back.
// It then compares the original trace to the read trace.
// If the traces are not equal, rapid will generate a minimal example
// that causes the test to fail.
func TestReadAndWriteTrace(t *testing.T) {
	parser := JSONParser{}
	writer := JSONWriter{}

	dir, err := os.MkdirTemp("", "example")
	if err != nil {
		log.Fatal(err)
	}
	defer os.RemoveAll(dir) // clean up

	rapid.Check(t, func(t *rapid.T) {
		trace := GetTraceGen().Draw(t, "Trace")
		filename := filepath.Join(dir, "trace.json")
		err := WriteAndReadTrace(parser, writer, trace, filename)
		if err != nil {
			t.Fatalf("error writing and reading trace: %v", err)
		}
	})
}

// This can be used to test writing and parsing traces, but does not make much sense
// for testing trace execution, since the generated traces are almost guaranteed to be nonsensical.
func GetTraceGen() *rapid.Generator[[]Step] {
	return rapid.SliceOf(GetStepGen())
}

func GetStepGen() *rapid.Generator[Step] {
	return rapid.Custom(func(t *rapid.T) Step {
		return Step{
			Action: GetActionGen().Draw(t, "Action"),
			State:  GetStateGen().Draw(t, "State"),
		}
	})
}