Inject stdin/out/err instead of always using os.Stdin/out/err

Signed-off-by: Dave Henderson <dhenderson@gmail.com>

5 files changed, 46 insertions, 16 deletions

diff --git a/internal/cmd/config.go b/internal/cmd/config.go
index 3db450af..f45f5ff1 100644
--- a/internal/cmd/config.go
+++ b/internal/cmd/config.go
@@ -48,6 +48,10 @@ func loadConfig(cmd *cobra.Command, args []string) (*config.Config, error) {
 		return nil, err
 	}
 
+	cfg.Stdin = cmd.InOrStdin()
+	cfg.Stdout = cmd.OutOrStdout()
+	cfg.Stderr = cmd.ErrOrStderr()
+
 	// reset defaults before validation
 	cfg.ApplyDefaults()
 
diff --git a/internal/cmd/config_test.go b/internal/cmd/config_test.go
index aa5e09f3..1bc82e09 100644
--- a/internal/cmd/config_test.go
+++ b/internal/cmd/config_test.go
@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"os"
@@ -63,7 +64,12 @@ func TestLoadConfig(t *testing.T) {
 	fs = afero.NewMemMapFs()
 	defer func() { fs = afero.NewOsFs() }()
 
+	stdin, stdout, stderr := &bytes.Buffer{}, &bytes.Buffer{}, &bytes.Buffer{}
 	cmd := &cobra.Command{}
+	cmd.SetIn(stdin)
+	cmd.SetOut(stdout)
+	cmd.SetErr(stderr)
+
 	cmd.Args = optionalExecArgs
 	cmd.Flags().StringSlice("file", []string{"-"}, "...")
 	cmd.Flags().StringSlice("out", []string{"-"}, "...")
@@ -80,9 +86,11 @@ func TestLoadConfig(t *testing.T) {
 		OutputFiles:   []string{"-"},
 		LDelim:        "{{",
 		RDelim:        "}}",
-		PostExecInput: os.Stdin,
-		OutWriter:     os.Stdout,
+		PostExecInput: stdin,
 		PluginTimeout: 5 * time.Second,
+		Stdin:         stdin,
+		Stdout:        stdout,
+		Stderr:        stderr,
 	}
 	assert.NoError(t, err)
 	assert.EqualValues(t, expected, out)
@@ -94,9 +102,11 @@ func TestLoadConfig(t *testing.T) {
 		OutputFiles:   []string{"-"},
 		LDelim:        "{{",
 		RDelim:        "}}",
-		PostExecInput: os.Stdin,
-		OutWriter:     os.Stdout,
+		PostExecInput: stdin,
 		PluginTimeout: 5 * time.Second,
+		Stdin:         stdin,
+		Stdout:        out.Stdout,
+		Stderr:        stderr,
 	}
 	assert.NoError(t, err)
 	assert.EqualValues(t, expected, out)
@@ -110,9 +120,11 @@ func TestLoadConfig(t *testing.T) {
 		ExecPipe:      true,
 		PostExec:      []string{"tr", "[a-z]", "[A-Z]"},
 		PostExecInput: out.PostExecInput,
-		OutWriter:     out.PostExecInput,
 		OutputFiles:   []string{"-"},
 		PluginTimeout: 5 * time.Second,
+		Stdin:         stdin,
+		Stdout:        out.Stdout,
+		Stderr:        stderr,
 	}
 	assert.NoError(t, err)
 	assert.EqualValues(t, expected, out)
diff --git a/internal/cmd/main.go b/internal/cmd/main.go
index 3c7862d5..9217a725 100644
--- a/internal/cmd/main.go
+++ b/internal/cmd/main.go
@@ -18,7 +18,7 @@ import (
 )
 
 // postRunExec - if templating succeeds, the command following a '--' will be executed
-func postRunExec(ctx context.Context, cfg *config.Config) error {
+func postRunExec(ctx context.Context, cfg *config.Config, stdout, stderr io.Writer) error {
 	args := cfg.PostExec
 	if len(args) > 0 {
 		log := zerolog.Ctx(ctx)
@@ -29,8 +29,8 @@ func postRunExec(ctx context.Context, cfg *config.Config) error {
 		// nolint: gosec
 		c := exec.CommandContext(ctx, name, args...)
 		c.Stdin = cfg.PostExecInput
-		c.Stderr = os.Stderr
-		c.Stdout = os.Stdout
+		c.Stderr = stderr
+		c.Stdout = stdout
 
 		// make sure all signals are propagated
 		sigs := make(chan os.Signal, 1)
@@ -98,7 +98,7 @@ func NewGomplateCmd() *cobra.Command {
 			// Note: once stdin/out/err are externalized we should only do this
 			// if stdout isn't ending with its own newline!
 			if len(cfg.OutputFiles) == 0 || (len(cfg.OutputFiles) == 1 && cfg.OutputFiles[0] == "-") && !cfg.ExecPipe {
-				fmt.Fprintf(os.Stderr, "\n")
+				fmt.Fprintf(cmd.ErrOrStderr(), "\n")
 			}
 			log.Debug().Int("templatesRendered", gomplate.Metrics.TemplatesProcessed).
 				Int("errors", gomplate.Metrics.Errors).
@@ -108,7 +108,7 @@ func NewGomplateCmd() *cobra.Command {
 			if err != nil {
 				return err
 			}
-			return postRunExec(ctx, cfg)
+			return postRunExec(ctx, cfg, cmd.OutOrStdout(), cmd.ErrOrStderr())
 		},
 		Args: optionalExecArgs,
 	}
diff --git a/internal/cmd/main_test.go b/internal/cmd/main_test.go
index 5c688443..678d5979 100644
--- a/internal/cmd/main_test.go
+++ b/internal/cmd/main_test.go
@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"bytes"
 	"context"
 	"testing"
 
@@ -47,4 +48,11 @@ func TestRunMain(t *testing.T) {
 
 	err = Main(ctx, []string{"--bogus"}, nil, nil, nil)
 	assert.Error(t, err)
+
+	stdin := &bytes.Buffer{}
+	stdout := &bytes.Buffer{}
+	stderr := &bytes.Buffer{}
+	err = Main(ctx, []string{"-i", "hello"}, stdin, stdout, stderr)
+	assert.NoError(t, err)
+	assert.Equal(t, "hello", stdout.String())
 }
diff --git a/internal/config/configfile.go b/internal/config/configfile.go
index a20c95cb..9969648e 100644
--- a/internal/config/configfile.go
+++ b/internal/config/configfile.go
@@ -14,6 +14,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/hairyhenderson/gomplate/v3/internal/iohelpers"
 	"github.com/pkg/errors"
 	"gopkg.in/yaml.v3"
 )
@@ -59,8 +60,11 @@ type Config struct {
 	ExtraHeaders map[string]http.Header `yaml:"-"`
 
 	// internal use only, can't be injected in YAML
-	PostExecInput io.ReadWriter `yaml:"-"`
-	OutWriter     io.Writer     `yaml:"-"`
+	PostExecInput io.Reader `yaml:"-"`
+
+	Stdin  io.Reader `yaml:"-"`
+	Stdout io.Writer `yaml:"-"`
+	Stderr io.Writer `yaml:"-"`
 }
 
 var cfgContextKey = struct{}{}
@@ -452,12 +456,14 @@ func (c *Config) ApplyDefaults() {
 	}
 
 	if c.ExecPipe {
-		c.PostExecInput = &bytes.Buffer{}
-		c.OutWriter = c.PostExecInput
+		pipe := &bytes.Buffer{}
+		c.PostExecInput = pipe
 		c.OutputFiles = []string{"-"}
+
+		// --exec-pipe redirects standard out to the out pipe
+		c.Stdout = &iohelpers.NopCloser{Writer: pipe}
 	} else {
-		c.PostExecInput = os.Stdin
-		c.OutWriter = os.Stdout
+		c.PostExecInput = c.Stdin
 	}
 
 	if c.PluginTimeout == 0 {