Merge pull request #188 from vito/runs-errgroup

better error handling

bass/util.bass

@@ -0,0 +1,4 @@
+; just for eyeballing files
+(defn ls paths
+  (from (linux/alpine)
+    ($ ls -al & $paths)))

pkg/bass/errors.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"sort"
+	"strings"
 
 	"github.com/agext/levenshtein"
 	"github.com/morikuni/aec"
@@ -19,7 +20,7 @@ import (
 type NiceError interface {
 	error
 
-	NiceError(io.Writer) error
+	NiceError(io.Writer, error) error
 }
 
 type FlagError struct {
@@ -31,8 +32,8 @@ func (err FlagError) Error() string {
 	return err.Err.Error()
 }
 
-func (err FlagError) NiceError(w io.Writer) error {
-	fmt.Fprintf(w, "\x1b[31m%s\x1b[0m\n", err)
+func (err FlagError) NiceError(w io.Writer, outer error) error {
+	fmt.Fprintln(w, aec.RedF.Apply(outer.Error()))
 	fmt.Fprintln(w)
 	fmt.Fprintln(w, "flags:")
 
@@ -80,8 +81,8 @@ func (err UnboundError) Error() string {
 	return fmt.Sprintf("unbound symbol: %s", err.Symbol)
 }
 
-func (unbound UnboundError) NiceError(w io.Writer) error {
-	_, err := fmt.Fprintf(w, aec.RedF.Apply("unbound symbol: %s")+"\n", unbound.Symbol)
+func (unbound UnboundError) NiceError(w io.Writer, outer error) error {
+	fmt.Fprintln(w, aec.RedF.Apply(outer.Error()))
 
 	similar := []Symbol{}
 	unbound.Scope.Each(func(k Symbol, _ Value) error {
@@ -119,7 +120,7 @@ func (unbound UnboundError) NiceError(w io.Writer) error {
 		fmt.Fprintf(w, "did you mean %s, perchance?\n", aec.Bold.Apply(string(similar[0])))
 	}
 
-	return err
+	return nil
 }
 
 type ArityError struct {
@@ -210,11 +211,12 @@ func (err *StructuredError) Error() string {
 		return err.Message
 	}
 
-	return fmt.Sprintf("%s; %s", err.Message, err.Fields)
+	return fmt.Sprintf("%s; fields: %s", err.Message, err.Fields)
 }
 
-func (structured *StructuredError) NiceError(w io.Writer) error {
-	fmt.Fprintln(w, aec.RedF.Apply(structured.Message))
+func (structured *StructuredError) NiceError(w io.Writer, outer error) error {
+	prefix, _, _ := strings.Cut(outer.Error(), "; fields: ")
+	fmt.Fprintln(w, aec.RedF.Apply(prefix))
 
 	if len(structured.Fields.Bindings) > 0 {
 		fmt.Fprintln(w)

pkg/bass/errors_test.go

@@ -3,6 +3,7 @@ package bass_test
 import (
 	"bufio"
 	"bytes"
+	"errors"
 	"fmt"
 	"testing"
 
@@ -25,7 +26,7 @@ func TestUnboundErrorNice(t *testing.T) {
 			"foo",
 			bass.Bindings{},
 			[]string{
-				aec.RedF.Apply(`unbound symbol: foo`),
+				aec.RedF.Apply(`wrapped: unbound symbol: foo`),
 			},
 		},
 		{
@@ -38,7 +39,7 @@ func TestUnboundErrorNice(t *testing.T) {
 				"f12":         bass.Null{},
 			},
 			output{
-				aec.RedF.Apply(`unbound symbol: f123`),
+				aec.RedF.Apply(`wrapped: unbound symbol: f123`),
 				``,
 				`similar bindings:`,
 				``,
@@ -61,8 +62,12 @@ func TestUnboundErrorNice(t *testing.T) {
 				Scope:  scope,
 			}
 
+			var nice bass.NiceError
+			err := fmt.Errorf("wrapped: %w", unboundErr)
+			is.True(errors.As(err, &nice))
+
 			out := new(bytes.Buffer)
-			is.NoErr(unboundErr.NiceError(out))
+			is.NoErr(nice.NiceError(out, err))
 
 			scanner := bufio.NewScanner(out)
 			for _, line := range example.Message {

pkg/bass/runs.go

@@ -3,10 +3,38 @@ package bass
 import (
 	"context"
 	"sync"
+
+	"github.com/hashicorp/go-multierror"
 )
 
 type Runs struct {
-	sync.WaitGroup
+	wg sync.WaitGroup
+
+	errs  error
+	errsL sync.Mutex
+}
+
+func (runs *Runs) Go(f func() error) {
+	runs.wg.Add(1)
+	go func() {
+		defer runs.wg.Done()
+		runs.record(f())
+	}()
+}
+
+func (runs *Runs) Wait() error {
+	runs.wg.Wait()
+	return runs.errs
+}
+
+func (runs *Runs) record(err error) {
+	runs.errsL.Lock()
+	if runs.errs != nil {
+		runs.errs = multierror.Append(runs.errs, err)
+	} else {
+		runs.errs = err
+	}
+	runs.errsL.Unlock()
 }
 
 type runsKey struct{}

pkg/bass/runs_test.go

@@ -0,0 +1,54 @@
+package bass_test
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/vito/bass/pkg/bass"
+	"github.com/vito/bass/pkg/basstest"
+	"github.com/vito/is"
+)
+
+func TestRuns(t *testing.T) {
+	is := is.New(t)
+
+	ctx := context.Background()
+	ctx, runs := bass.TrackRuns(ctx)
+
+	errorScpt := bass.NewInMemoryFile("error.bass", `
+		(defn main [msg]
+			(error msg))
+	`)
+
+	thunk1 := bass.MustThunk(errorScpt).AppendArgs(bass.String("oh no"))
+	thunk2 := bass.MustThunk(errorScpt).AppendArgs(bass.String("let's go"))
+
+	errCb := bass.Func("err-if-not-ok", "[ok?]", func(ok bool) error {
+		if !ok {
+			return fmt.Errorf("it failed!")
+		}
+
+		return nil
+	})
+
+	comb1, err := thunk1.Start(ctx, errCb)
+	is.NoErr(err)
+
+	comb2, err := thunk2.Start(ctx, errCb)
+	is.NoErr(err)
+
+	_, err = basstest.Call(comb1, bass.NewEmptyScope(), bass.NewList())
+	is.True(err != nil)
+	is.Equal(err.Error(), "it failed!: oh no")
+
+	_, err = basstest.Call(comb2, bass.NewEmptyScope(), bass.NewList())
+	is.True(err != nil)
+	is.Equal(err.Error(), "it failed!: let's go")
+
+	err = runs.Wait()
+	is.True(err != nil)
+	is.True(strings.Contains(err.Error(), "it failed!: oh no"))
+	is.True(strings.Contains(err.Error(), "it failed!: let's go"))
+}

pkg/bass/thunk.go

@@ -200,11 +200,10 @@ func (thunk Thunk) Start(ctx context.Context, handler Combiner) (Combiner, error
 	var waitErr error
 
 	runs := RunsFromContext(ctx)
-	runs.Add(1)
+
 	wg := new(sync.WaitGroup)
 	wg.Add(1)
-	go func() {
-		defer runs.Done()
+	runs.Go(func() error {
 		defer wg.Done()
 
 		runErr := thunk.Run(ctx, io.Discard)
@@ -217,7 +216,9 @@ func (thunk Thunk) Start(ctx context.Context, handler Combiner) (Combiner, error
 		} else {
 			waitRes = res
 		}
-	}()
+
+		return waitErr
+	})
 
 	return Func(thunk.String(), "[]", func() (Value, error) {
 		wg.Wait()
@@ -289,6 +290,12 @@ func (thunk Thunk) WithArgs(args []Value) Thunk {
 	return thunk
 }
 
+// AppendArgs appends to the thunk's arg values.
+func (thunk Thunk) AppendArgs(args ...Value) Thunk {
+	thunk.Args = append(thunk.Args, args...)
+	return thunk
+}
+
 // WithEnv sets the thunk's env.
 func (thunk Thunk) WithEnv(env *Scope) Thunk {
 	thunk.Env = env

pkg/cli/error.go

@@ -28,8 +28,9 @@ func WriteError(ctx context.Context, err error) {
 		}
 	}
 
-	if nice, ok := err.(bass.NiceError); ok {
-		metaErr := nice.NiceError(out)
+	var nice bass.NiceError
+	if errors.As(err, &nice) {
+		metaErr := nice.NiceError(out, err)
 		if metaErr != nil {
 			fmt.Fprintf(out, aec.RedF.Apply("errored while erroring: %s")+"\n", metaErr)
 			fmt.Fprintf(out, aec.RedF.Apply("original error: %T: %s")+"\n", err, err)

pkg/cli/progress_error.go

@@ -27,8 +27,8 @@ func (err ProgressError) Error() string {
 	return fmt.Sprintf("%s: %s", err.msg, stripUselessPart(rootErr.Error()))
 }
 
-func (progErr ProgressError) NiceError(w io.Writer) error {
-	fmt.Fprintf(w, aec.RedF.Apply("%s")+"\n", progErr.Error())
+func (progErr ProgressError) NiceError(w io.Writer, outer error) error {
+	fmt.Fprintln(w, aec.RedF.Apply(outer.Error()))
 	fmt.Fprintln(w)
 
 	progErr.prog.Summarize(textio.NewPrefixWriter(w, "  "))

project.bass

@@ -1,27 +1,22 @@
-; location to track dependency resolution
-(def *memos*
-  *dir*/bass/bass.lock)
+; file for memoized dependency resolution
+(def *memos* *dir*/bass/bass.lock)
 
 ; load dependencies
 (use (.git (linux/alpine/git))
      (*dir*/bass/bass.bass)
+     (*dir*/bass/util.bass)
      (git:github/vito/bass-loop/ref/main/bass/github.bass))
 
 ; standard suite of validations for the repo
 (defn checks [src]
-  {:build-linux (ls (bass:build src "dev" "linux" "amd64"))
-   :build-darwin (ls (bass:build src "dev" "darwin" "amd64")
+  {:build-linux (util:ls (bass:build src "dev" "linux" "amd64"))
+   :build-darwin (util:ls (bass:build src "dev" "darwin" "amd64")
                      (bass:build src "dev" "darwin" "arm64"))
-   :build-windows (ls (bass:build src "dev" "windows" "amd64"))
-   :docs (ls (bass:docs src))
+   :build-windows (util:ls (bass:build src "dev" "windows" "amd64"))
+   :docs (util:ls (bass:docs src))
    :test (bass:tests src ["./..."])
    :nix (bass:nix-checks src)})
 
-; just for eyeballing the files
-(defn ls paths
-  (from (linux/alpine)
-    ($ ls -al & $paths)))
-
 ; called by bass-loop
 (defn github-hook [event client]
   (github:check-hook event client git checks))