Merge pull request #5 from dusk125/fix-callval

go.mod

@@ -1,3 +1,11 @@
 module github.com/gopxl/mainthread/v2
 
 go 1.21
+
+require github.com/stretchr/testify v1.8.4
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

mainthread.go

@@ -83,12 +83,16 @@ func CallErr(f func() error) error {
 }
 
 // CallVal queues function f on the main thread and returns a value returned by f.
-func CallVal[T any](f func() T) T {
+func CallVal[T any](f func() T) (t T) {
 	checkRun()
 	respChan := <-donePool
 	defer returnDone(respChan)
 	callQueue <- func() {
 		respChan <- f()
 	}
-	return (<-respChan).(T)
+	v := <-respChan
+	if v != nil {
+		return v.(T)
+	}
+	return
 }

mainthread_test.go

@@ -2,9 +2,11 @@ package mainthread_test
 
 import (
 	"errors"
+	"io"
 	"testing"
 
 	"github.com/gopxl/mainthread/v2"
+	"github.com/stretchr/testify/require"
 )
 
 func BenchmarkCall(b *testing.B) {
@@ -43,3 +45,50 @@ func BenchmarkCallVal(b *testing.B) {
 	}
 	mainthread.Run(run)
 }
+
+func TestCallVal_Resp(t *testing.T) {
+	run := func() {
+		f := func() *int {
+			v := 1
+			return &v
+		}
+		v := mainthread.CallVal(f)
+		require.NotNil(t, v)
+		require.Equal(t, 1, *v)
+	}
+	mainthread.Run(run)
+}
+
+func TestCallVal_nilResp(t *testing.T) {
+	run := func() {
+		f := func() *int {
+			return nil
+		}
+		v := mainthread.CallVal(f)
+		require.Nil(t, v)
+	}
+	mainthread.Run(run)
+}
+
+func TestCallErr_Resp(t *testing.T) {
+	run := func() {
+		f := func() error {
+			return io.EOF
+		}
+		v := mainthread.CallErr(f)
+		require.NotNil(t, v)
+		require.EqualError(t, v, io.EOF.Error())
+	}
+	mainthread.Run(run)
+}
+
+func TestCallErr_nilResp(t *testing.T) {
+	run := func() {
+		f := func() error {
+			return nil
+		}
+		v := mainthread.CallErr(f)
+		require.NoError(t, v)
+	}
+	mainthread.Run(run)
+}