Print exactly what will be written to file during a real ensure run

Author: carolynvs

cmd/dep/ensure.go

@@ -119,7 +119,7 @@ func (cmd *ensureCommand) Run(ctx *dep.Ctx, args []string) error {
 	defer sm.Release()
 
 	params := p.MakeParams()
-	if *verbose || cmd.dryRun {
+	if *verbose {
 		params.Trace = true
 		params.TraceLogger = log.New(os.Stderr, "", 0)
 	}
@@ -166,12 +166,47 @@ func (cmd *ensureCommand) Run(ctx *dep.Ctx, args []string) error {
 	writeV := !vendorExists && solution != nil
 
 	if cmd.dryRun {
-		return nil
+		return printDryRunActions(sw, writeV)
 	}
 
 	return errors.Wrap(sw.WriteAllSafe(writeV), "grouped write of manifest, lock and vendor")
 }
 
+func printDryRunActions(sw dep.SafeWriter, writeV bool) error {
+	if sw.Manifest != nil {
+		fmt.Println("Would have written the following manifest.json:")
+		m, err := sw.Manifest.MarshalJSON()
+		if err != nil {
+			return errors.Wrap(err, "ensure DryRun cannot read manifest")
+		}
+		fmt.Println(string(m))
+	}
+
+	if sw.Lock != nil {
+		fmt.Println("Would have written the following lock.json:")
+		m, err := sw.Lock.MarshalJSON()
+		if err != nil {
+			return errors.Wrap(err, "ensure DryRun cannot read lock")
+		}
+		fmt.Println(string(m))
+	}
+
+	if writeV {
+		fmt.Println("Would have written the following projects to the vendor directory:")
+		for _, project := range sw.NewLock.Projects() {
+			prj := project.Ident()
+			rev := dep.GetRevisionFromVersion(project.Version())
+			if prj.Source == "" {
+				fmt.Printf("%s@%s\n", prj.ProjectRoot, rev)
+			} else {
+				fmt.Printf("%s -> %s@%s\n", prj.ProjectRoot, prj.Source, rev)
+			}
+		}
+	}
+
+	return nil
+}
+
 func applyUpdateArgs(args []string, params *gps.SolveParameters) {
 	// When -update is specified without args, allow every project to change versions, regardless of the lock file
 	if len(args) == 0 {

lock.go

@@ -102,16 +102,7 @@ func (l *Lock) MarshalJSON() ([]byte, error) {
 		}
 
 		v := lp.Version()
-		// Figure out how to get the underlying revision
-		switch tv := v.(type) {
-		case gps.UnpairedVersion:
-			// TODO we could error here, if we want to be very defensive about not
-			// allowing a lock to be written if without an immmutable revision
-		case gps.Revision:
-			ld.Revision = tv.String()
-		case gps.PairedVersion:
-			ld.Revision = tv.Underlying().String()
-		}
+		ld.Revision = GetRevisionFromVersion(v)
 
 		switch v.Type() {
 		case gps.IsBranch:
@@ -134,6 +125,20 @@ func (l *Lock) MarshalJSON() ([]byte, error) {
 	return buf.Bytes(), err
 }
 
+func GetRevisionFromVersion(v gps.Version) string {
+	// Figure out how to get the underlying revision
+	switch tv := v.(type) {
+	case gps.UnpairedVersion:
+	// TODO we could error here, if we want to be very defensive about not
+	// allowing a lock to be written if without an immmutable revision
+	case gps.Revision:
+		return tv.String()
+	case gps.PairedVersion:
+		return tv.Underlying().String()
+	}
+	return ""
+}
+
 // LockFromInterface converts an arbitrary gps.Lock to dep's representation of a
 // lock. If the input is already dep's *lock, the input is returned directly.
 //