Implementation of cat-ls exercise

.gitignore

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+!*/assets

Go.AllowList.gitignore

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+
+
+
+# Allowlisting gitignore template for GO projects prevents us
+# from adding various unwanted local files, such as generated
+# files, developer configurations or IDE-specific files etc.
+#
+# Recommended: Go.AllowList.gitignore
+
+# Ignore everything
+*
+
+# But not these files...
+!/.gitignore
+
+!*.go
+!go.sum
+!go.mod
+
+!README.md
+!LICENSE
+
+# !Makefile
+
+# ...even if they are in subdirectories
+!*/

cli-files/go-cat/assets/dew.txt

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+“A World of Dew” by Kobayashi Issa
+
+A world of dew,
+And within every dewdrop
+A world of struggle.

cli-files/go-cat/assets/for_you.txt

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+Sonia Sanchez “Haiku [for you]”
+
+Love between us is
+speech and breath. Loving you is
+a long river running.

cli-files/go-cat/assets/rain.txt

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+“The Taste of Rain” by Jack Kerouac
+
+The taste
+Of rain
+—Why kneel?

cli-files/go-cat/cmd/root.go

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+/*
+Copyright © 2022 NAME HERE <EMAIL ADDRESS>
+
+*/
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+// rootCmd represents the base command when called without any subcommands
+func NewRoodCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "go-cat",
+		Short: "Go implementation of cat",
+		Long:  `Works like cat`,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			// Don't do anything if we didn't get an arg
+			if len(args) < 1 {
+				return nil
+			}
+			path := args[0]
+
+			// Get data about the file so we can do this safely
+			file, err := os.Stat(path)
+			if err != nil {
+				return err
+			}
+
+			// If it's a directory, do the right thing and error
+			if file.IsDir() {
+				return fmt.Errorf("go-cat: %s: Is a directory", path)
+			}
+
+			// Read the data from the file
+			// https://pkg.go.dev/os#ReadFile
+			data, err := os.ReadFile(path)
+			if err != nil {
+				return err
+			}
+
+			// Print those lovely bytes
+			out := cmd.OutOrStdout()
+			out.Write(data)
+
+			return nil
+		},
+	}
+}
+
+func Execute() {
+	rootCmd := NewRoodCmd()
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}

cli-files/go-cat/cmd/root_test.go

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+package cmd
+
+import (
+	"bytes"
+	"io/ioutil"
+	"testing"
+)
+
+func TestRootCmd(t *testing.T) {
+	cmd := NewRoodCmd()
+	b := bytes.NewBufferString("")
+	cmd.SetOut(b)
+	cmd.SetArgs([]string{})
+	cmd.Execute()
+	out, err := ioutil.ReadAll(b)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := ``
+	if string(out) != expected {
+		t.Fatalf("expected \"%s\" got \"%s\"", expected, string(out))
+	}
+}
+
+func TestRootCmdWithFile(t *testing.T) {
+	cmd := NewRoodCmd()
+	b := bytes.NewBufferString("")
+	cmd.SetOut(b)
+	cmd.SetArgs([]string{"../assets/dew.txt"})
+	cmd.Execute()
+	out, err := ioutil.ReadAll(b)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := `“A World of Dew” by Kobayashi Issa
+
+A world of dew,
+And within every dewdrop
+A world of struggle.`
+	if string(out) != expected {
+		t.Fatalf("expected \"%s\" got \"%s\"", expected, string(out))
+	}
+}

cli-files/go-cat/go.mod

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+module go-cat
+
+go 1.18
+
+require github.com/spf13/cobra v1.5.0
+
+require (
+	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+)

cli-files/go-cat/go.sum

@@ -0,0 +1,10 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
+github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/spf13/cobra v1.5.0 h1:X+jTBEBqF0bHN+9cSMgmfuvv2VHJ9ezmFNf9Y/XstYU=
+github.com/spf13/cobra v1.5.0/go.mod h1:dWXEIy2H428czQCjInthrTRUg7yKbok+2Qi/yBIJoUM=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

cli-files/go-cat/main.go

@@ -0,0 +1,11 @@
+/*
+Copyright © 2022 NAME HERE <EMAIL ADDRESS>
+
+*/
+package main
+
+import "go-cat/cmd"
+
+func main() {
+	cmd.Execute()
+}

cli-files/go-ls/cmd/root.go

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+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+func NewRoodCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "go-ls",
+		Short: "go-ls is a re-implementation of the ls command",
+		Args:  cobra.ArbitraryArgs,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			// By default, ls the current directory
+			dir := "."
+			// If an argument was passed, use the first as our directory
+			if len(args) > 0 {
+				dir = args[0]
+			}
+
+			// Stat the file so we can check if it's a directory or not before
+			// we try to read it as a directory using ReadDir. os.ReadDir will
+			// generates an error if the thing you pass to it is not a directory.
+			// https://pkg.go.dev/os#Stat
+			fileInfo, err := os.Stat(dir)
+			if err != nil {
+				return err
+			}
+
+			// We can only list the contents of a directory.
+			// To match the real ls, if we're asked to ls a file, we'll just print
+			// out the file's name.
+			// https://pkg.go.dev/io/fs#FileInfo
+			if fileInfo.IsDir() == false {
+				fmt.Fprintln(cmd.OutOrStdout(), fileInfo.Name())
+				return nil
+			}
+
+			// Read this directory to get a list of files
+			// https://pkg.go.dev/os#ReadDir
+			files, err := os.ReadDir(dir)
+			if err != nil {
+				return err
+			}
+			// Iterate through each file in the directory, printing the file name
+			for _, file := range files {
+				fmt.Fprintln(cmd.OutOrStdout(), file.Name())
+			}
+			return nil
+		},
+	}
+}
+
+func Execute() {
+	rootCmd := NewRoodCmd()
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}

cli-files/go-ls/cmd/root_test.go

@@ -0,0 +1,61 @@
+package cmd
+
+import (
+	"bytes"
+	"io/ioutil"
+	"testing"
+)
+
+func TestRootCmd(t *testing.T) {
+	cmd := NewRoodCmd()
+	b := bytes.NewBufferString("")
+	cmd.SetOut(b)
+	cmd.SetArgs([]string{})
+	cmd.Execute()
+	out, err := ioutil.ReadAll(b)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := `root.go
+root_test.go
+`
+	if string(out) != expected {
+		t.Fatalf("expected \"%s\" got \"%s\"", expected, string(out))
+	}
+}
+
+func TestRootCmdRelative(t *testing.T) {
+	cmd := NewRoodCmd()
+	b := bytes.NewBufferString("")
+	cmd.SetOut(b)
+	cmd.SetArgs([]string{"../assets"})
+	cmd.Execute()
+	out, err := ioutil.ReadAll(b)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := `dew.txt
+for_you.txt
+rain.txt
+`
+	if string(out) != expected {
+		t.Fatalf("expected \"%s\" got \"%s\"", expected, string(out))
+	}
+}
+
+func TestRootCmdFile(t *testing.T) {
+	cmd := NewRoodCmd()
+	b := bytes.NewBufferString("")
+	cmd.SetOut(b)
+	cmd.SetArgs([]string{"../assets/dew.txt"})
+	cmd.Execute()
+	out, err := ioutil.ReadAll(b)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := `dew.txt
+`
+	if string(out) != expected {
+		t.Fatalf("expected \"%s\" got \"%s\"", expected, string(out))
+	}
+}

cli-files/go-ls/go.mod

@@ -0,0 +1,10 @@
+module go-ls
+
+go 1.18
+
+require github.com/spf13/cobra v1.5.0
+
+require (
+	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+)

cli-files/go-ls/go.sum

@@ -0,0 +1,10 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
+github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/spf13/cobra v1.5.0 h1:X+jTBEBqF0bHN+9cSMgmfuvv2VHJ9ezmFNf9Y/XstYU=
+github.com/spf13/cobra v1.5.0/go.mod h1:dWXEIy2H428czQCjInthrTRUg7yKbok+2Qi/yBIJoUM=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

cli-files/go-ls/main.go

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+package main
+
+import (
+	"go-ls/cmd"
+)
+
+func main() {
+	cmd.Execute()
+}