add t.Output

Author: mxey

engine.go

@@ -12,6 +12,7 @@ import (
 	"encoding/binary"
 	"flag"
 	"fmt"
+	"io"
 	"log"
 	"os"
 	"path/filepath"
@@ -778,6 +779,39 @@ func (t *T) Log(args ...any) {
 	}
 }
 
+// Output returns a Writer that writes to the same test output stream as T.Log.
+// The output is indented like T.Log lines, but Output does not
+// add source locations or newlines. The output is internally line
+// buffered, and a call to T.Log or the end of the test will implicitly
+// flush the buffer, followed by a newline. After a test function and all its
+// parents return, neither Output nor the Write method may be called.
+//
+// If running on Go <= 1.25, where testing's t.Output is not available,
+// it falls back to using t.Log.
+func (t *T) Output() io.Writer {
+	if t.rawLog != nil {
+		return t.rawLog.Writer()
+	} else if t.tbLog {
+		if tout, ok := t.tb.(interface{ Output() io.Writer }); ok {
+			return tout.Output()
+		} else {
+			return &tbWriter{t.tb}
+		}
+	} else {
+		return io.Discard
+	}
+}
+
+type tbWriter struct {
+	tb
+}
+
+func (w *tbWriter) Write(b []byte) (int, error) {
+	w.tb.Helper()
+	w.tb.Logf("%s", b)
+	return len(b), nil
+}
+
 // Skipf is equivalent to [T.Logf] followed by [T.SkipNow].
 func (t *T) Skipf(format string, args ...any) {
 	if t.tbLog {

engine_test.go

@@ -7,6 +7,7 @@
 package rapid
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"reflect"
@@ -259,3 +260,17 @@ func (ignoreErrorsTB) Errorf(string, ...interface{}) {}
 func (ignoreErrorsTB) Fatal(...interface{})          {}
 func (ignoreErrorsTB) Fatalf(string, ...interface{}) {}
 func (ignoreErrorsTB) Fail()                         {}
+
+func TestOutputRawLog(t *testing.T) {
+	t.Parallel()
+
+	msg := []byte("Hello World")
+
+	out := captureTestOutput(t, func(t *T) {
+		t.Output().Write(msg)
+	}, nil)
+
+	if !bytes.Contains(out, msg) {
+		t.Errorf("expected output to contain %q, got: %q", msg, out)
+	}
+}