basic go-cat implementation

Author: tgvashworth

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

@@ -0,0 +1,5 @@
+“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

@@ -0,0 +1,5 @@
+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

@@ -0,0 +1,5 @@
+“The Taste of Rain” by Jack Kerouac
+
+The taste
+Of rain
+—Why kneel?

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

@@ -17,7 +17,34 @@ func NewRoodCmd() *cobra.Command {
 		Use:   "go-cat",
 		Short: "Go implementation of cat",
 		Long:  `Works like cat`,
-		Run: func(cmd *cobra.Command, args []string) {
+		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)
+			}
+
+			data, err := os.ReadFile(path)
+			if err != nil {
+				return err
+			}
+
+			// Print those lovely bytes
+			out := cmd.OutOrStdout()
+			out.Write(data)
+
+			return nil
 		},
 	}
 }

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

@@ -21,3 +21,23 @@ func TestRootCmd(t *testing.T) {
 		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))
+	}
+}