Fix error handling in mage build

* print gofmt errors
* don't error on lint failures
* explanatory comments and fix an error text

diff --git a/magefile.go b/magefile.go
index 3800f49b6eb0a2f7d97e86c7f089e797c3e13a46..89bbd7481505a27c2a43cb98a411325f15380b7f 100644 (file)
--- a/magefile.go
+++ b/magefile.go
@@ -5,6 +5,7 @@ package main
 import (
        "bytes"
        "errors"
+       "fmt"
        "io/ioutil"
        "os"
        "path/filepath"
@@ -124,14 +125,28 @@ func Fmt() error {
                return err
        }
        failed := false
+       first := true
        for _, pkg := range pkgs {
                files, err := filepath.Glob(filepath.Join(pkg, "*.go"))
                if err != nil {
                        return nil
                }
                for _, f := range files {
-                       if err := sh.Run("gofmt", "-l", f); err != nil {
-                               failed = false
+                       // gofmt doesn't exit with non-zero when it finds unformatted code
+                       // so we have to explicitly look for output, and if we find any, we
+                       // should fail this target.
+                       s, err := sh.Output("gofmt", "-l", f)
+                       if err != nil {
+                               fmt.Printf("ERROR: running gofmt on %q: %v\n", f, err)
+                               failed = true
+                       }
+                       if s != "" {
+                               if first {
+                                       fmt.Println("The following files are not gofmt'ed:")
+                                       first = false
+                               }
+                               failed = true
+                               fmt.Println(s)
                        }
                }
        }
@@ -164,12 +179,15 @@ func Lint() error {
        }
        failed := false
        for _, pkg := range pkgs {
-               if _, err := sh.Exec(nil, os.Stderr, os.Stderr, "golint", "-set_exit_status", pkg); err != nil {
+               // We don't actually want to fail this target if we find golint errors,
+               // so we don't pass -set_exit_status, but we still print out any failures.
+               if _, err := sh.Exec(nil, os.Stderr, nil, "golint", pkg); err != nil {
+                       fmt.Printf("ERROR: running go lint on %q: %v\n", pkg, err)
                        failed = true
                }
        }
        if failed {
-               return errors.New("golint errors!")
+               return errors.New("errors running golint")
        }
        return nil
 }
@@ -178,7 +196,7 @@ func Lint() error {
 func Vet() error {
        mg.Deps(govendor)
        if err := sh.Run("govendor", "vet", "+local"); err != nil {
-               return errors.New("go vet errors!")
+               return fmt.Errorf("error running govendor: %v", err)
        }
        return nil
 }