Merge pull request #1534 from mmontes11/pr-diff-use-default-pager

Using default pager in gh pr diff

pkg/cmd/pr/diff/diff.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"os"
+	"os/exec"
 	"strings"
 
 	"github.com/cli/cli/api"
@@ -13,6 +15,7 @@ import (
 	"github.com/cli/cli/pkg/cmd/pr/shared"
 	"github.com/cli/cli/pkg/cmdutil"
 	"github.com/cli/cli/pkg/iostreams"
+	"github.com/google/shlex"
 	"github.com/spf13/cobra"
 )
 
@@ -90,6 +93,12 @@ func diffRun(opts *DiffOptions) error {
 		return err
 	}
 
+	if opts.IO.IsStdoutTTY() {
+		if pager := os.Getenv("PAGER"); pager != "" {
+			return runPager(pager, diff, opts.IO.Out)
+		}
+	}
+
 	diffLines := bufio.NewScanner(diff)
 	for diffLines.Scan() {
 		diffLine := diffLines.Text()
@@ -134,3 +143,14 @@ func isRemovalLine(dl string) bool {
 func validColorFlag(c string) bool {
 	return c == "auto" || c == "always" || c == "never"
 }
+
+var runPager = func(pager string, diff io.Reader, out io.Writer) error {
+	args, err := shlex.Split(pager)
+	if err != nil {
+		return err
+	}
+	pagerCmd := exec.Command(args[0], args[1:]...)
+	pagerCmd.Stdin = diff
+	pagerCmd.Stdout = out
+	return pagerCmd.Run()
+}

pkg/cmd/pr/diff/diff_test.go

@@ -2,8 +2,10 @@ package diff
 
 import (
 	"bytes"
+	"io"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"testing"
 
 	"github.com/cli/cli/context"
@@ -131,8 +133,13 @@ func TestPRDiff_notty(t *testing.T) {
 }
 
 func TestPRDiff_tty(t *testing.T) {
+	pager := os.Getenv("PAGER")
 	http := &httpmock.Registry{}
-	defer http.Verify(t)
+	defer func() {
+		os.Setenv("PAGER", pager)
+		http.Verify(t)
+	}()
+	os.Setenv("PAGER", "")
 	http.StubResponse(200, bytes.NewBufferString(`
 		{ "data": { "repository": { "pullRequests": { "nodes": [
 			{ "url": "https://github.com/OWNER/REPO/pull/123",
@@ -149,6 +156,38 @@ func TestPRDiff_tty(t *testing.T) {
 	assert.Contains(t, output.String(), "\x1b[32m+site: bin/gh\x1b[m")
 }
 
+func TestPRDiff_pager(t *testing.T) {
+	realRunPager := runPager
+	pager := os.Getenv("PAGER")
+	http := &httpmock.Registry{}
+	defer func() {
+		runPager = realRunPager
+		os.Setenv("PAGER", pager)
+		http.Verify(t)
+	}()
+	runPager = func(pager string, diff io.Reader, out io.Writer) error {
+		_, err := io.Copy(out, diff)
+		return err
+	}
+	os.Setenv("PAGER", "fakepager")
+	http.StubResponse(200, bytes.NewBufferString(`
+	{ "data": { "repository": { "pullRequests": { "nodes": [
+		{ "url": "https://github.com/OWNER/REPO/pull/123",
+		  "number": 123,
+		  "id": "foobar123",
+		  "headRefName": "feature",
+			"baseRefName": "master" }
+	] } } } }`))
+	http.StubResponse(200, bytes.NewBufferString(testDiff))
+	output, err := runCommand(http, nil, true, "")
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+	if diff := cmp.Diff(testDiff, output.String()); diff != "" {
+		t.Errorf("command output did not match:\n%s", diff)
+	}
+}
+
 const testDiff = `diff --git a/.github/workflows/releases.yml b/.github/workflows/releases.yml
 index 73974448..b7fc0154 100644
 --- a/.github/workflows/releases.yml