Added Repeat tests

TODO.txt

@@ -1,5 +1,5 @@
-Write Repeat tests
 Think about not requiring so much Pos() when making messages
+Think about changing "consume" to "commit"
 Rename Seq2 to Seq
 Document Seq
 Should MakeState be private now that there's Run?

gigaparsec.go

@@ -379,25 +379,26 @@ func Pipe[In, Ignore, Through any](p Parser[In, Ignore]) func(Through) Parser[In
 // It succeeds if and only if p succeeds at least minCount times.
 // It consumes if and only if at least one of the applications of p consumes.
 func Repeat[In, Out any](minCount int, p Parser[In, Out]) Parser[In, []Out] {
-	return func(s State[In]) (Result[In, []Out], error) {
+	return func(state State[In]) (Result[In, []Out], error) {
 		var values []Out
 		var consumed bool
-		next := s
+		currState := state
 		for {
-			result, err := p(next)
+			result, err := p(currState)
 			if err != nil {
 				return Result[In, []Out]{}, fmt.Errorf("AtLeastN: %w", err)
 			}
 			consumed = consumed || result.Consumed()
 			var value Out
 			var success bool
-			success, value, next = result.Status()
+			success, value, nextState := result.Status()
 			if !success {
 				if len(values) >= minCount {
-					return Succeed(consumed, values, next, MessageOK(s.Pos())), nil
+					return Succeed(consumed, values, currState, MessageOK(state.Pos())), nil
 				}
 				return Fail[In, []Out](consumed, result.Message()), nil
 			}
+			currState = nextState
 			values = append(values, value)
 		}
 	}

parser_test.go

@@ -4,6 +4,8 @@ package gigaparsec_test
 
 import (
 	"bytes"
+	"errors"
+	"io"
 	"testing"
 
 	"git.codemonkeysoftware.net/b/gigaparsec"
@@ -138,24 +140,69 @@ func TestEnd(t *testing.T) {
 }
 
 func TestRepeat(t *testing.T) {
-	t.Run("succeeds iff number of successes ≥ minCount", rapid.MakeCheck(func(t *rapid.T) {
-		const good byte = 'o'
-		const bad byte = 'x'
 	const maxParses = 100
-
+	t.Run("succeeds iff number of successes ≥ minCount", rapid.MakeCheck(func(t *rapid.T) {
 		minCount := rapid.IntRange(0, maxParses).Draw(t, "minCount")
 		successes := rapid.IntRange(0, maxParses).Draw(t, "successes")
+		shouldSucceed := successes >= minCount
 
-		input := append(ptest.SliceOfN(good, successes), bad)
-		p := gigaparsec.Repeat(minCount, gigaparsec.Match(good))
-		result, err := p(gigaparsec.MakeState(bytes.NewReader(input)))
+		input := append(ptest.SliceOfN(true, successes), false)
+		p := gigaparsec.Repeat(minCount, gigaparsec.Match(true))
+		result, err := p(gigaparsec.MakeState(gigaparsec.SliceReaderAt[bool](input)))
 
 		must.NoError(t, err)
-		success, _, _ := result.Status()
-		test.EqOp(t, successes >= minCount, success, test.Sprint("expected successes ≥ minCount"))
+		success, _, next := result.Status()
+		test.EqOp(t, shouldSucceed, success)
+		if success {
+			test.EqOp(t, uint64(successes), next.Pos())
+		}
 	}))
-	t.Run("consumes iff at least one application consumes", Todo)
-	t.Run("fails on error", Todo)
-	t.Run("position is unchanged on failure", Todo)
-	t.Run("position follows last success on overall success", Todo)
+	t.Run("consumes iff at least one application consumes", rapid.MakeCheck(func(t *rapid.T) {
+		type Token struct {
+			Consume, Succeed bool
+		}
+		// p will succeed and consume based on the values in the parsed token.
+		var p gigaparsec.Parser[Token, Token] = func(s gigaparsec.State[Token]) (gigaparsec.Result[Token, Token], error) {
+			buf := make([]Token, 1)
+			_, next, err := s.Read(buf)
+			if errors.Is(err, io.EOF) {
+				return gigaparsec.Fail[Token, Token](false, gigaparsec.MessageEnd(s.Pos())), nil
+			}
+			if err != nil {
+				return gigaparsec.Result[Token, Token]{}, err
+			}
+			tok := buf[0]
+			if tok.Succeed {
+				return gigaparsec.Succeed(tok.Consume, tok, next, gigaparsec.MessageOK(s.Pos())), nil
+			} else {
+				return gigaparsec.Fail[Token, Token](tok.Consume, gigaparsec.MakeMessage(s.Pos(), "false", "true")), nil
+			}
+		}
+
+		input := rapid.Map(rapid.SliceOfN(rapid.Just(Token{Succeed: true}), 0, 100),
+			func(ts []Token) []Token { return append(ts, Token{}) }).Draw(t, "input")
+		consumeAt := rapid.Ptr(rapid.IntRange(0, len(input)-1), true).Draw(t, "consumeAt")
+		if consumeAt != nil {
+			input[*consumeAt].Consume = true
+		}
+		shouldConsume := consumeAt != nil
+
+		result, err := gigaparsec.Repeat(0, p)(gigaparsec.MakeState(gigaparsec.SliceReaderAt[Token](input)))
+		must.NoError(t, err)
+		test.EqOp(t, shouldConsume, result.Consumed())
+	}))
+	t.Run("does not consume on empty input", func(t *testing.T) {
+		p := gigaparsec.Repeat(0, gigaparsec.Match(0))
+		result, err := p(gigaparsec.MakeState(gigaparsec.SliceReaderAt[int](nil)))
+		must.NoError(t, err)
+		must.False(t, result.Consumed())
+	})
+	t.Run("fails on error", func(t *testing.T) {
+		expectedErr := errors.New("it broke")
+		p := gigaparsec.Repeat(0, gigaparsec.Match(byte(0)))
+		result, err := p(gigaparsec.MakeState(ptest.ErrReaderAt(expectedErr)))
+		succeeded, _, _ := result.Status()
+		test.ErrorIs(t, err, expectedErr)
+		test.False(t, succeeded)
+	})
 }