feat(mr): support minimal unified diff output for mr diff

- Modify mr diff output to provide a minimum unified diff support
- Document glab_pager configuration in glab config command

commands/config/config.go

@@ -4,16 +4,17 @@ import (
 	"fmt"
 
 	"github.com/MakeNowJust/heredoc"
+	"github.com/spf13/cobra"
+
 	"github.com/profclems/glab/commands/cmdutils"
 	"github.com/profclems/glab/internal/config"
 	"github.com/profclems/glab/pkg/glinstance"
-	"github.com/spf13/cobra"
 )
 
 var isGlobal bool
 
 func NewCmdConfig(f *cmdutils.Factory) *cobra.Command {
-	var configCmd = &cobra.Command{
+	configCmd := &cobra.Command{
 		Use:   "config [flags]",
 		Short: `Set and get glab settings`,
 		Long: heredoc.Doc(`Get and set key/value strings.
@@ -26,6 +27,7 @@ Current respected settings:
 - editor: if unset, defaults to environment variables.
 - visual: alternative for editor. if unset, defaults to environment variables.
 - glamour_style: Your desired markdown renderer style. Options are dark, light, notty. Custom styles are allowed set a custom style https://github.com/charmbracelet/glamour#styles
+- glab_pager: Your desired pager command to use (e.g. less -R)
 	`),
 		Aliases: []string{"conf"},
 	}
@@ -133,7 +135,7 @@ Specifying the --hostname flag also saves in the global config file
 }
 
 func NewCmdConfigInit(f *cmdutils.Factory) *cobra.Command {
-	var configInitCmd = &cobra.Command{
+	configInitCmd := &cobra.Command{
 		Use:   "init",
 		Short: "Shows a prompt to set basic glab configuration",
 		Long: `Update the configuration by setting a key to a value.

commands/mr/diff/diff.go

@@ -13,9 +13,10 @@ import (
 	"github.com/profclems/glab/pkg/iostreams"
 
 	"github.com/MakeNowJust/heredoc"
+	"github.com/xanzy/go-gitlab"
+
 	"github.com/profclems/glab/commands/cmdutils"
 	"github.com/profclems/glab/commands/mr/mrutils"
-	"github.com/xanzy/go-gitlab"
 
 	"github.com/spf13/cobra"
 )
@@ -45,7 +46,6 @@ func NewCmdDiff(f *cmdutils.Factory, runF func(*DiffOptions) error) *cobra.Comma
 		`),
 		Args: cobra.MaximumNArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-
 			if repoOverride, _ := cmd.Flags().GetString("repo"); repoOverride != "" && len(args) == 0 {
 				return &cmdutils.FlagError{Err: errors.New("argument required when using the --repo flag")}
 			}
@@ -97,14 +97,9 @@ func diffRun(opts *DiffOptions) error {
 			return fmt.Errorf("could not find merge request diff: %w", err)
 		}
 		for _, diffLine := range diffVersion.Diffs {
-			if diffLine.RenamedFile {
-				diffOut.WriteString("-" + diffLine.OldPath + "\n")
-			}
-			if diffLine.NewFile || diffLine.RenamedFile {
-				diffOut.WriteString("+" + diffLine.NewPath + "\n")
-			} else {
-				diffOut.WriteString(diffLine.OldPath + "\n")
-			}
+			// output the unified diff header
+			diffOut.WriteString("--- " + diffLine.OldPath + "\n")
+			diffOut.WriteString("+++ " + diffLine.NewPath + "\n")
 
 			diffOut.WriteString(diffLine.Diff)
 		}

pkg/iostreams/iostreams.go

@@ -20,10 +20,10 @@ type IOStreams struct {
 	StdOut io.Writer
 	StdErr io.Writer
 
-	IsaTTY         bool //stdout is a tty
-	IsErrTTY       bool //stderr is a tty
-	IsInTTY        bool //stdin is a tty
-	promptDisabled bool //disable prompting for input
+	IsaTTY         bool // stdout is a tty
+	IsErrTTY       bool // stderr is a tty
+	IsInTTY        bool // stdin is a tty
+	promptDisabled bool // disable prompting for input
 
 	is256ColorEnabled bool
 
@@ -171,7 +171,7 @@ func (s *IOStreams) TerminalWidth() int {
 	return TerminalWidth(s.StdOut)
 }
 
-//IsOutputTTY returns true if both stdout and stderr is TTY
+// IsOutputTTY returns true if both stdout and stderr is TTY
 func (s *IOStreams) IsOutputTTY() bool {
 	return s.IsErrTTY && s.IsaTTY
 }