Merge pull request #31 from blocklayerhq/fix-fs-scratch

fs: don't panic when handling scratch output results

dagger/component.go

@@ -2,6 +2,7 @@ package dagger
 
 import (
 	"context"
+	"os"
 )
 
 type Component struct {
@@ -37,7 +38,11 @@ func (c *Component) Validate() error {
 
 // Return this component's compute script.
 func (c *Component) ComputeScript() (*Script, error) {
-	return c.Value().Get("#dagger.compute").Script()
+	v := c.Value().Get("#dagger.compute")
+	if !v.Exists() {
+		return nil, os.ErrNotExist
+	}
+	return v.Script()
 }
 
 // Compute the configuration for this component.
@@ -62,6 +67,10 @@ func (c *Component) Compute(ctx context.Context, s Solver, out Fillable) (FS, er
 func (c *Component) Execute(ctx context.Context, fs FS, out Fillable) (FS, error) {
 	script, err := c.ComputeScript()
 	if err != nil {
+		// If the component has no script, then do not fail.
+		if os.IsNotExist(err) {
+			return fs, nil
+		}
 		return fs, err
 	}
 	return script.Execute(ctx, fs, out)

dagger/fs.go

@@ -2,6 +2,7 @@ package dagger
 
 import (
 	"context"
+	"os"
 	"path"
 
 	"github.com/moby/buildkit/client/llb"
@@ -47,6 +48,12 @@ func (fs FS) ReadFile(ctx context.Context, filename string) ([]byte, error) {
 	if err := (&fs).solve(ctx); err != nil {
 		return nil, err
 	}
+	// NOTE: llb.Scratch is represented by a `nil` reference. If solve result is
+	// Scratch, then `fs.output` is `nil`.
+	if fs.output == nil {
+		return nil, os.ErrNotExist
+	}
+
 	return fs.output.ReadFile(ctx, bkgw.ReadRequest{Filename: filename})
 }
 
@@ -55,6 +62,12 @@ func (fs FS) ReadDir(ctx context.Context, dir string) ([]Stat, error) {
 	if err := (&fs).solve(ctx); err != nil {
 		return nil, err
 	}
+
+	// NOTE: llb.Scratch is represented by a `nil` reference. If solve result is
+	// Scratch, then `fs.output` is `nil`.
+	if fs.output == nil {
+		return []Stat{}, nil
+	}
 	st, err := fs.output.ReadDir(ctx, bkgw.ReadDirRequest{
 		Path: dir,
 	})

dagger/script.go

@@ -10,7 +10,7 @@ type Script struct {
 	v *Value
 }
 
-func (s Script) Validate() error {
+func (s *Script) Validate() error {
 	// FIXME this crashes when a script is incomplete or empty
 	return s.Value().Validate("#Script")
 }

examples/tests/test.sh

@@ -22,9 +22,8 @@ test::compute(){
       "$dagger" compute "$d"/compute/invalid/int
   test::one "Compute: invalid struct should fail" --exit=1 --stdout= \
       "$dagger" compute "$d"/compute/invalid/struct
-  # XXX https://github.com/blocklayerhq/dagger/issues/22
-  #test::one "Compute: noop should succeed" --exit=0 --stdout="{}"  \
-  #    "$dagger" compute "$d"/compute/noop
+  test::one "Compute: noop should succeed" --exit=0 --stdout='{"empty":{},"realempty":{},"withprops":{}}'  \
+      "$dagger" compute "$d"/compute/noop
   # XXX https://github.com/blocklayerhq/dagger/issues/28
   #test::one "Compute: unresolved should fail" --exit=1 --stdout=  \
   #    "$dagger" compute "$d"/compute/invalid/undefined_prop