Improve error handling when resolving codec

And remove the go.work files that masked a faulty test setup.

This is replaced with replace statements in the examples, which is OK as those are only used in
tests/as examples.

README.md

@@ -12,7 +12,8 @@ client, err := execrpc.StartClient(
 			ClientRawOptions: execrpc.ClientRawOptions{
 				Version: 1,
 				Cmd:     "go",
-				Args:    []string{"run", "./examples/servers/typed"},
+				Dir:  "./examples/servers/typed"
+				Args:    []string{"run", "."},
 			},
 			Codec: codecs.JSONCodec[model.ExampleRequest, model.ExampleResponse]{},
 		},

client.go

@@ -106,7 +106,7 @@ func StartClientRaw(opts ClientRawOptions) (*ClientRaw, error) {
 	}
 
 	if err := conn.Start(); err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed start server: %s: %s", err, conn.stdErr.String())
 	}
 
 	if opts.OnMessage == nil {

client_test.go

@@ -18,7 +18,8 @@ func TestExecRaw(t *testing.T) {
 		execrpc.ClientRawOptions{
 			Version: 1,
 			Cmd:     "go",
-			Args:    []string{"run", "./examples/servers/raw"},
+			Dir:     "./examples/servers/raw",
+			Args:    []string{"run", "."},
 		})
 
 	c.Assert(err, qt.IsNil)
@@ -41,7 +42,8 @@ func newTestClient(t testing.TB, codec codecs.Codec[model.ExampleRequest, model.
 			ClientRawOptions: execrpc.ClientRawOptions{
 				Version: 1,
 				Cmd:     "go",
-				Args:    []string{"run", "./examples/servers/typed"},
+				Dir:     "./examples/servers/typed",
+				Args:    []string{"run", "."},
 				Env:     env,
 			},
 			Codec: codec,
@@ -62,7 +64,8 @@ func TestExecTyped(t *testing.T) {
 				ClientRawOptions: execrpc.ClientRawOptions{
 					Version: 1,
 					Cmd:     "go",
-					Args:    []string{"run", "./examples/servers/typed"},
+					Dir:     "./examples/servers/typed",
+					Args:    []string{"run", "."},
 					Env:     env,
 					Timeout: 4 * time.Second,
 				},
@@ -108,7 +111,8 @@ func TestExecTyped(t *testing.T) {
 				ClientRawOptions: execrpc.ClientRawOptions{
 					Version: 1,
 					Cmd:     "go",
-					Args:    []string{"run", "./examples/servers/typed"},
+					Dir:     "./examples/servers/typed",
+					Args:    []string{"run", "."},
 					Env:     []string{"EXECRPC_SEND_TWO_LOG_MESSAGES=true"},
 					Timeout: 4 * time.Second,
 					OnMessage: func(msg execrpc.Message) {

examples/servers/raw/go.mod

@@ -2,4 +2,12 @@ module github.com/bep/execrpc/examples/servers/raw
 
 go 1.19
 
-require golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 // indirect
+require github.com/bep/execrpc v0.3.0
+
+require (
+	github.com/bep/helpers v0.1.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.0.2 // indirect
+	golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 // indirect
+)
+
+replace github.com/bep/execrpc => ../../..

examples/servers/raw/go.sum

@@ -1,2 +1,23 @@
+github.com/bep/execrpc v0.3.0 h1:cZCobakmpgFSWRtJBmOmksSirSQZzz3m3+Ojc0YroGs=
+github.com/bep/execrpc v0.3.0/go.mod h1:wDgrl/LwaUp6+EFCx0w1uvqP1cbwln/4OhB608TIREk=
+github.com/bep/helpers v0.1.0 h1:HFLG+W6axHackmKMk0houEnz9G2aiBrDMZyOvL9J0WM=
+github.com/bep/helpers v0.1.0/go.mod h1:/QpHdmcPagDw7+RjkLFCvnlUc8lQ5kg4KDrEkb2Yyco=
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/frankban/quicktest v1.14.3 h1:FJKSZTDHjyhriyC81FLQ0LY93eSai0ZyR/ZIkd3ZUKE=
+github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
+github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/pelletier/go-toml/v2 v2.0.2 h1:+jQXlF3scKIcSEKkdHzXhCTDLPFi5r1wnK6yPS+49Gw=
+github.com/pelletier/go-toml/v2 v2.0.2/go.mod h1:MovirKjgVRESsAvNZlAjtFwV867yGuwRkXbG66OzopI=
+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/rogpeppe/go-internal v1.8.1 h1:geMPLpDpQOgVyCg5z5GoRwLHepNdb71NXb67XFkP+Eg=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.2 h1:4jaiDzPyXQvSd7D0EjG45355tLlV3VOECpq10pLC+8s=
+github.com/stretchr/testify v1.7.2/go.mod h1:R6va5+xMeoiuVRoj+gSkQ7d3FALtqAAGI1FQKckRals=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 h1:uVc8UZUe6tr40fFVnUP5Oj+veunVezqYl9z7DYw9xzw=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+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=

examples/servers/typed/go.mod

@@ -2,4 +2,11 @@ module github.com/bep/execrpc/examples/servers/typed
 
 go 1.19
 
-require golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 // indirect
+require (
+	github.com/bep/execrpc v0.3.0 // indirect
+	github.com/bep/helpers v0.1.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.0.2 // indirect
+	golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 // indirect
+)
+
+replace github.com/bep/execrpc => ../../..

examples/servers/typed/go.sum

@@ -1,2 +1,14 @@
+github.com/bep/execrpc v0.3.0 h1:cZCobakmpgFSWRtJBmOmksSirSQZzz3m3+Ojc0YroGs=
+github.com/bep/execrpc v0.3.0/go.mod h1:wDgrl/LwaUp6+EFCx0w1uvqP1cbwln/4OhB608TIREk=
+github.com/bep/helpers v0.1.0 h1:HFLG+W6axHackmKMk0houEnz9G2aiBrDMZyOvL9J0WM=
+github.com/bep/helpers v0.1.0/go.mod h1:/QpHdmcPagDw7+RjkLFCvnlUc8lQ5kg4KDrEkb2Yyco=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pelletier/go-toml/v2 v2.0.2 h1:+jQXlF3scKIcSEKkdHzXhCTDLPFi5r1wnK6yPS+49Gw=
+github.com/pelletier/go-toml/v2 v2.0.2/go.mod h1:MovirKjgVRESsAvNZlAjtFwV867yGuwRkXbG66OzopI=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.2/go.mod h1:R6va5+xMeoiuVRoj+gSkQ7d3FALtqAAGI1FQKckRals=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 h1:uVc8UZUe6tr40fFVnUP5Oj+veunVezqYl9z7DYw9xzw=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

go.mod

@@ -3,12 +3,15 @@ module github.com/bep/execrpc
 go 1.18
 
 require (
-	github.com/bep/helpers v0.1.0 // indirect
-	github.com/frankban/quicktest v1.14.3 // indirect
+	github.com/bep/helpers v0.1.0
+	github.com/frankban/quicktest v1.14.3
+	github.com/pelletier/go-toml/v2 v2.0.2
+	golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4
+)
+
+require (
 	github.com/google/go-cmp v0.5.8 // indirect
 	github.com/kr/pretty v0.3.0 // indirect
 	github.com/kr/text v0.2.0 // indirect
-	github.com/pelletier/go-toml/v2 v2.0.2 // indirect
 	github.com/rogpeppe/go-internal v1.8.1 // indirect
-	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 // indirect
 )

go.sum

@@ -1,12 +1,12 @@
 github.com/bep/helpers v0.1.0 h1:HFLG+W6axHackmKMk0houEnz9G2aiBrDMZyOvL9J0WM=
 github.com/bep/helpers v0.1.0/go.mod h1:/QpHdmcPagDw7+RjkLFCvnlUc8lQ5kg4KDrEkb2Yyco=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/frankban/quicktest v1.14.2 h1:SPb1KFFmM+ybpEjPUhCCkZOM5xlovT5UbrMvWnXyBns=
-github.com/frankban/quicktest v1.14.2/go.mod h1:mgiwOwqx65TmIk1wJ6Q7wvnVMocbUorkibMOrVTHZps=
+github.com/frankban/quicktest v1.14.3 h1:FJKSZTDHjyhriyC81FLQ0LY93eSai0ZyR/ZIkd3ZUKE=
 github.com/frankban/quicktest v1.14.3/go.mod h1:mgiwOwqx65TmIk1wJ6Q7wvnVMocbUorkibMOrVTHZps=
-github.com/google/go-cmp v0.5.7 h1:81/ik6ipDQS2aGcBfIN5dHDB36BwrStyeAQquSYCV4o=
 github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
+github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
 github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
@@ -18,15 +18,19 @@ github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/pelletier/go-toml/v2 v2.0.2 h1:+jQXlF3scKIcSEKkdHzXhCTDLPFi5r1wnK6yPS+49Gw=
 github.com/pelletier/go-toml/v2 v2.0.2/go.mod h1:MovirKjgVRESsAvNZlAjtFwV867yGuwRkXbG66OzopI=
 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
+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/rogpeppe/go-internal v1.6.1 h1:/FiVV8dS/e+YqF2JvO3yXRFbBLTIuSDkuC7aBOAvL+k=
 github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
+github.com/rogpeppe/go-internal v1.8.1 h1:geMPLpDpQOgVyCg5z5GoRwLHepNdb71NXb67XFkP+Eg=
 github.com/rogpeppe/go-internal v1.8.1/go.mod h1:JeRgkft04UBgHMgCIwADu4Pn6Mtm5d4nPKWu0nJ5d+o=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.2 h1:4jaiDzPyXQvSd7D0EjG45355tLlV3VOECpq10pLC+8s=
 github.com/stretchr/testify v1.7.2/go.mod h1:R6va5+xMeoiuVRoj+gSkQ7d3FALtqAAGI1FQKckRals=
-golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 h1:uVc8UZUe6tr40fFVnUP5Oj+veunVezqYl9z7DYw9xzw=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

server.go

@@ -1,7 +1,6 @@
 package execrpc
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -42,13 +41,13 @@ func NewServer[Q, R any](opts ServerOptions[Q, R]) (*Server[Q, R], error) {
 	if opts.Call == nil {
 		return nil, fmt.Errorf("opts: Call function is required")
 	}
+
 	if opts.Codec == nil {
-		if opts.Codec == nil {
-			var err error
-			opts.Codec, err = codecs.ForName[R, Q](os.Getenv(envClientCodec))
-			if err != nil {
-				return nil, errors.New("opts: Codec is required")
-			}
+		codecName := os.Getenv(envClientCodec)
+		var err error
+		opts.Codec, err = codecs.ForName[R, Q](codecName)
+		if err != nil {
+			return nil, fmt.Errorf("failed to resolve codec from env variable %s with value %q (set by client); it can optionally be set in ServerOptions", envClientCodec, codecName)
 		}
 	}