Task: Increase test coverage, includes refactor

Adds test cases to increase test coverage.
Refactors code to enable adding tests by reducing the number of
locations where `os.Exit()` is called from.

commands_test.go

@@ -0,0 +1,305 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/spf13/cobra"
+)
+
+func getRootCommand() *cobra.Command {
+	return newCommandCLI()
+}
+
+func TestRootCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	if !strings.Contains(result.Output, "Usage:") {
+		t.Error("Expected usage message to be printed out, but the usage message was not found.")
+	}
+
+}
+
+func TestRootCmd_VerboseLong(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "--verbose")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	if !verbose {
+		t.Error("Expected verbose to be true")
+	}
+}
+
+func TestRootCmd_VerboseShort(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "-v")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	if !verbose {
+		t.Error("Expected verbose to be true")
+	}
+}
+
+func TestRootCmd_TrimLong(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "--trim")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	if !trimOutput {
+		t.Error("Expected trimOutput to be true")
+	}
+}
+
+func TestRootCmd_TrimShort(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "-t")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	if !trimOutput {
+		t.Error("Expected trimOutput to be true")
+	}
+}
+
+func TestRootCmd_ToJsonLong(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "--tojson")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	if !outputToJSON {
+		t.Error("Expected outputToJSON to be true")
+	}
+}
+
+func TestRootCmd_ToJsonShort(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "-j")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	if !outputToJSON {
+		t.Error("Expected outputToJSON to be true")
+	}
+}
+
+func TestReadCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "read examples/sample.yaml b.c")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	assertResult(t, "2\n", result.Output)
+}
+
+func TestReadCmd_Error(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "read")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide filename`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestReadCmd_ErrorEmptyFilename(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "read  ")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide filename`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestReadCmd_ErrorUnreadableFile(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "read fake-unknown")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to unknown file")
+	}
+	expectedOutput := `open fake-unknown: no such file or directory`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestReadCmd_ErrorBadPath(t *testing.T) {
+	content := `b:
+  d:
+    e:
+      - 3
+      - 4
+    f:
+      - 1
+      - 2
+`
+	filename := writeTempYamlFile(content)
+	defer removeTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := runCmd(cmd, fmt.Sprintf("read %s b.d.*.[x]", filename))
+	if result.Error == nil {
+		t.Fatal("Expected command to fail due to invalid path")
+	}
+	expectedOutput := `Error accessing array: strconv.ParseInt: parsing "x": invalid syntax`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestReadCmd_Verbose(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "-v read examples/sample.yaml b.c")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	assertResult(t, "2\n", result.Output)
+}
+
+func TestReadCmd_NoTrim(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "--trim=false read examples/sample.yaml b.c")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	assertResult(t, "2\n\n", result.Output)
+}
+
+func TestReadCmd_ToJson(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "-j read examples/sample.yaml b.c")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	assertResult(t, "2\n", result.Output)
+}
+
+func TestNewCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "new b.c 3")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+`
+	assertResult(t, expectedOutput, result.Output)
+}
+
+func TestNewCmd_Error(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "new b.c")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide <path_to_update> <value>`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestNewCmd_Verbose(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "-v new b.c 3")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+`
+	assertResult(t, expectedOutput, result.Output)
+}
+
+func TestNewCmd_ToJson(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "-j new b.c 3")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `{"b":{"c":3}}
+`
+	assertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := writeTempYamlFile(content)
+	defer removeTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := runCmd(cmd, fmt.Sprintf("write %s b.c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 7
+`
+	assertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_Error(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "write")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide <filename> <path_to_update> <value>`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestWriteCmd_ErrorUnreadableFile(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "write fake-unknown a.b 3")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to unknown file")
+	}
+	expectedOutput := `open fake-unknown: no such file or directory`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestWriteCmd_Verbose(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := writeTempYamlFile(content)
+	defer removeTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := runCmd(cmd, fmt.Sprintf("-v write %s b.c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 7
+`
+	assertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_Inplace(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := writeTempYamlFile(content)
+	defer removeTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := runCmd(cmd, fmt.Sprintf("write -i %s b.c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	gotOutput := readTempYamlFile(filename)
+	expectedOutput := `b:
+  c: 7`
+	assertResult(t, expectedOutput, gotOutput)
+}

data_navigator.go

@@ -1,9 +1,10 @@
 package main
 
 import (
+	"fmt"
 	"strconv"
 
-	yaml "gopkg.in/yaml.v2"
+	"gopkg.in/yaml.v2"
 )
 
 func entryInSlice(context yaml.MapSlice, key interface{}) *yaml.MapItem {
@@ -79,10 +80,12 @@ func writeArray(context interface{}, paths []string, value interface{}) []interf
 	log.Debugf("\tarray %v\n", array)
 
 	rawIndex := paths[0]
-	index, err := strconv.ParseInt(rawIndex, 10, 64)
+	index, _ := strconv.ParseInt(rawIndex, 10, 64)
-	if err != nil {
+	// writeArray is only called by updatedChildValue which handles parsing the
-		die("Error accessing array: %v", err)
+	// index, as such this renders this dead code.
-	}
+	// if err != nil {
+	// 	return array, fmt.Errorf("Error accessing array: %v", err)
+	// }
 	for index >= int64(len(array)) {
 		array = append(array, nil)
 	}
@@ -96,7 +99,7 @@ func writeArray(context interface{}, paths []string, value interface{}) []interf
 	return array
 }
 
-func readMap(context yaml.MapSlice, head string, tail []string) interface{} {
+func readMap(context yaml.MapSlice, head string, tail []string) (interface{}, error) {
 	if head == "*" {
 		return readMapSplat(context, tail)
 	}
@@ -109,21 +112,25 @@ func readMap(context yaml.MapSlice, head string, tail []string) interface{} {
 	return calculateValue(value, tail)
 }
 
-func readMapSplat(context yaml.MapSlice, tail []string) interface{} {
+func readMapSplat(context yaml.MapSlice, tail []string) (interface{}, error) {
 	var newArray = make([]interface{}, len(context))
 	var i = 0
 	for _, entry := range context {
 		if len(tail) > 0 {
-			newArray[i] = recurse(entry.Value, tail[0], tail[1:])
+			val, err := recurse(entry.Value, tail[0], tail[1:])
+			if err != nil {
+				return nil, err
+			}
+			newArray[i] = val
 		} else {
 			newArray[i] = entry.Value
 		}
 		i++
 	}
-	return newArray
+	return newArray, nil
 }
 
-func recurse(value interface{}, head string, tail []string) interface{} {
+func recurse(value interface{}, head string, tail []string) (interface{}, error) {
 	switch value.(type) {
 	case []interface{}:
 		if head == "*" {
@@ -131,37 +138,40 @@ func recurse(value interface{}, head string, tail []string) interface{} {
 		}
 		index, err := strconv.ParseInt(head, 10, 64)
 		if err != nil {
-			die("Error accessing array: %v", err)
+			return nil, fmt.Errorf("Error accessing array: %v", err)
 		}
 		return readArray(value.([]interface{}), index, tail)
 	case yaml.MapSlice:
 		return readMap(value.(yaml.MapSlice), head, tail)
 	default:
-		return nil
+		return nil, nil
 	}
 }
 
-func readArray(array []interface{}, head int64, tail []string) interface{} {
+func readArray(array []interface{}, head int64, tail []string) (interface{}, error) {
 	if head >= int64(len(array)) {
-		return nil
+		return nil, nil
 	}
 
 	value := array[head]
-
 	return calculateValue(value, tail)
 }
 
-func readArraySplat(array []interface{}, tail []string) interface{} {
+func readArraySplat(array []interface{}, tail []string) (interface{}, error) {
 	var newArray = make([]interface{}, len(array))
 	for index, value := range array {
-		newArray[index] = calculateValue(value, tail)
+		val, err := calculateValue(value, tail)
+		if err != nil {
+			return nil, err
 		}
-	return newArray
+		newArray[index] = val
+	}
+	return newArray, nil
 }
 
-func calculateValue(value interface{}, tail []string) interface{} {
+func calculateValue(value interface{}, tail []string) (interface{}, error) {
 	if len(tail) > 0 {
 		return recurse(value, tail[0], tail[1:])
 	}
-	return value
+	return value, nil
 }

data_navigator_test.go

@@ -2,27 +2,20 @@ package main
 
 import (
 	"fmt"
-	"os"
 	"sort"
 	"testing"
 
-	logging "github.com/op/go-logging"
 	yaml "gopkg.in/yaml.v2"
 )
 
-func TestMain(m *testing.M) {
-	backend.SetLevel(logging.ERROR, "")
-	logging.SetBackend(backend)
-	os.Exit(m.Run())
-}
-
 func TestReadMap_simple(t *testing.T) {
 	var data = parseData(`
 ---
 b:
   c: 2
 `)
-	assertResult(t, 2, readMap(data, "b", []string{"c"}))
+	got, _ := readMap(data, "b", []string{"c"})
+	assertResult(t, 2, got)
 }
 
 func TestReadMap_splat(t *testing.T) {
@@ -32,7 +25,8 @@ mapSplat:
   item1: things
   item2: whatever
 `)
-	var result = readMap(data, "mapSplat", []string{"*"}).([]interface{})
+	res, _ := readMap(data, "mapSplat", []string{"*"})
+	result := res.([]interface{})
 	var actual = []string{result[0].(string), result[1].(string)}
 	sort.Strings(actual)
 	assertResult(t, "[things whatever]", fmt.Sprintf("%v", actual))
@@ -48,7 +42,8 @@ mapSplatDeep:
     cats: apples
 `)
 
-	var result = readMap(data, "mapSplatDeep", []string{"*", "cats"}).([]interface{})
+	res, _ := readMap(data, "mapSplatDeep", []string{"*", "cats"})
+	result := res.([]interface{})
 	var actual = []string{result[0].(string), result[1].(string)}
 	sort.Strings(actual)
 	assertResult(t, "[apples bananas]", fmt.Sprintf("%v", actual))
@@ -60,7 +55,8 @@ func TestReadMap_key_doesnt_exist(t *testing.T) {
 b:
   c: 2
 `)
-	assertResult(t, nil, readMap(data, "b.x.f", []string{"c"}))
+	got, _ := readMap(data, "b.x.f", []string{"c"})
+	assertResult(t, nil, got)
 }
 
 func TestReadMap_recurse_against_string(t *testing.T) {
@@ -68,7 +64,8 @@ func TestReadMap_recurse_against_string(t *testing.T) {
 ---
 a: cat
 `)
-	assertResult(t, nil, readMap(data, "a", []string{"b"}))
+	got, _ := readMap(data, "a", []string{"b"})
+	assertResult(t, nil, got)
 }
 
 func TestReadMap_with_array(t *testing.T) {
@@ -79,7 +76,64 @@ b:
     - 3
     - 4
 `)
-	assertResult(t, 4, readMap(data, "b", []string{"d", "1"}))
+	got, _ := readMap(data, "b", []string{"d", "1"})
+	assertResult(t, 4, got)
+}
+
+func TestReadMap_with_array_and_bad_index(t *testing.T) {
+	var data = parseData(`
+---
+b:
+  d:
+    - 3
+    - 4
+`)
+	_, err := readMap(data, "b", []string{"d", "x"})
+	if err == nil {
+		t.Fatal("Expected error due to invalid path")
+	}
+	expectedOutput := `Error accessing array: strconv.ParseInt: parsing "x": invalid syntax`
+	assertResult(t, expectedOutput, err.Error())
+}
+
+func TestReadMap_with_mapsplat_array_and_bad_index(t *testing.T) {
+	var data = parseData(`
+---
+b:
+  d:
+    e:
+      - 3
+      - 4
+    f:
+      - 1
+      - 2
+`)
+	_, err := readMap(data, "b", []string{"d", "*", "x"})
+	if err == nil {
+		t.Fatal("Expected error due to invalid path")
+	}
+	expectedOutput := `Error accessing array: strconv.ParseInt: parsing "x": invalid syntax`
+	assertResult(t, expectedOutput, err.Error())
+}
+
+func TestReadMap_with_arraysplat_map_array_and_bad_index(t *testing.T) {
+	var data = parseData(`
+---
+b:
+  d:
+    - names:
+        - fred
+        - smith
+    - names:
+        - sam
+        - bo
+`)
+	_, err := readMap(data, "b", []string{"d", "*", "names", "x"})
+	if err == nil {
+		t.Fatal("Expected error due to invalid path")
+	}
+	expectedOutput := `Error accessing array: strconv.ParseInt: parsing "x": invalid syntax`
+	assertResult(t, expectedOutput, err.Error())
 }
 
 func TestReadMap_with_array_out_of_bounds(t *testing.T) {
@@ -90,7 +144,8 @@ b:
     - 3
     - 4
 `)
-	assertResult(t, nil, readMap(data, "b", []string{"d", "3"}))
+	got, _ := readMap(data, "b", []string{"d", "3"})
+	assertResult(t, nil, got)
 }
 
 func TestReadMap_with_array_out_of_bounds_by_1(t *testing.T) {
@@ -101,7 +156,8 @@ b:
     - 3
     - 4
 `)
-	assertResult(t, nil, readMap(data, "b", []string{"d", "2"}))
+	got, _ := readMap(data, "b", []string{"d", "2"})
+	assertResult(t, nil, got)
 }
 
 func TestReadMap_with_array_splat(t *testing.T) {
@@ -114,7 +170,8 @@ e:
     name: Sam
     thing: dog
 `)
-	assertResult(t, "[Fred Sam]", fmt.Sprintf("%v", readMap(data, "e", []string{"*", "name"})))
+	got, _ := readMap(data, "e", []string{"*", "name"})
+	assertResult(t, "[Fred Sam]", fmt.Sprintf("%v", got))
 }
 
 func TestWrite_really_simple(t *testing.T) {
@@ -158,7 +215,8 @@ b:
 `)
 
 	updated := writeMap(data, []string{"b", "d", "f"}, "4")
-	assertResult(t, "4", readMap(updated, "b", []string{"d", "f"}))
+	got, _ := readMap(updated, "b", []string{"d", "f"})
+	assertResult(t, "4", got)
 }
 
 func TestWrite_array(t *testing.T) {
@@ -180,7 +238,8 @@ b:
 `)
 
 	updated := writeMap(data, []string{"b", "0"}, "4")
-	assertResult(t, "4", readMap(updated, "b", []string{"0"}))
+	got, _ := readMap(updated, "b", []string{"0"})
+	assertResult(t, "4", got)
 }
 
 func TestWrite_new_array_deep(t *testing.T) {
@@ -193,7 +252,8 @@ b:
 - c: "4"`
 
 	updated := writeMap(data, []string{"b", "0", "c"}, "4")
-	assertResult(t, expected, yamlToString(updated))
+	got, _ := yamlToString(updated)
+	assertResult(t, expected, got)
 }
 
 func TestWrite_new_map_array_deep(t *testing.T) {
@@ -203,7 +263,8 @@ b:
 `)
 
 	updated := writeMap(data, []string{"b", "d", "0"}, "4")
-	assertResult(t, "4", readMap(updated, "b", []string{"d", "0"}))
+	got, _ := readMap(updated, "b", []string{"d", "0"})
+	assertResult(t, "4", got)
 }
 
 func TestWrite_add_to_array(t *testing.T) {
@@ -217,8 +278,8 @@ b:
 - bb`
 
 	updated := writeMap(data, []string{"b", "1"}, "bb")
-
+	got, _ := yamlToString(updated)
-	assertResult(t, expected, yamlToString(updated))
+	assertResult(t, expected, got)
 }
 
 func TestWrite_with_no_tail(t *testing.T) {

json_converter.go

@@ -2,17 +2,18 @@ package main
 
 import (
 	"encoding/json"
+	"fmt"
 	"strconv"
 
 	yaml "gopkg.in/yaml.v2"
 )
 
-func jsonToString(context interface{}) string {
+func jsonToString(context interface{}) (string, error) {
 	out, err := json.Marshal(toJSON(context))
 	if err != nil {
-		die("error printing yaml as json: ", err)
+		return "", fmt.Errorf("error printing yaml as json: %v", err)
 	}
-	return string(out)
+	return string(out), nil
 }
 
 func toJSON(context interface{}) interface{} {

json_converter_test.go

@@ -10,7 +10,8 @@ func TestJsonToString(t *testing.T) {
 b:
   c: 2
 `)
-	assertResult(t, "{\"b\":{\"c\":2}}", jsonToString(data))
+	got, _ := jsonToString(data)
+	assertResult(t, "{\"b\":{\"c\":2}}", got)
 }
 
 func TestJsonToString_withIntKey(t *testing.T) {
@@ -19,7 +20,8 @@ func TestJsonToString_withIntKey(t *testing.T) {
 b:
   2: c
 `)
-	assertResult(t, `{"b":{"2":"c"}}`, jsonToString(data))
+	got, _ := jsonToString(data)
+	assertResult(t, `{"b":{"2":"c"}}`, got)
 }
 
 func TestJsonToString_withBoolKey(t *testing.T) {
@@ -28,7 +30,8 @@ func TestJsonToString_withBoolKey(t *testing.T) {
 b:
   false: c
 `)
-	assertResult(t, `{"b":{"false":"c"}}`, jsonToString(data))
+	got, _ := jsonToString(data)
+	assertResult(t, `{"b":{"false":"c"}}`, got)
 }
 
 func TestJsonToString_withArray(t *testing.T) {
@@ -38,5 +41,6 @@ b:
   - item: one
   - item: two
 `)
-	assertResult(t, "{\"b\":[{\"item\":\"one\"},{\"item\":\"two\"}]}", jsonToString(data))
+	got, _ := jsonToString(data)
+	assertResult(t, "{\"b\":[{\"item\":\"one\"},{\"item\":\"two\"}]}", got)
 }

utils_test.go

@@ -1,14 +1,35 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
+	"io/ioutil"
 	"os"
 	"reflect"
+	"strings"
 	"testing"
 
+	"github.com/spf13/cobra"
 	yaml "gopkg.in/yaml.v2"
 )
 
+type resulter struct {
+	Error   error
+	Output  string
+	Command *cobra.Command
+}
+
+func runCmd(c *cobra.Command, input string) resulter {
+	buf := new(bytes.Buffer)
+	c.SetOutput(buf)
+	c.SetArgs(strings.Split(input, " "))
+
+	err := c.Execute()
+	output := buf.String()
+
+	return resulter{err, output, c}
+}
+
 func parseData(rawData string) yaml.MapSlice {
 	var parsedData yaml.MapSlice
 	err := yaml.Unmarshal([]byte(rawData), &parsedData)
@@ -38,3 +59,22 @@ func assertResultWithContext(t *testing.T, expectedValue interface{}, actualValu
 		t.Error(": expected <", expectedValue, "> but got <", actualValue, ">")
 	}
 }
+
+func writeTempYamlFile(content string) string {
+	tmpfile, _ := ioutil.TempFile("", "testyaml")
+	defer func() {
+		_ = tmpfile.Close()
+	}()
+
+	_, _ = tmpfile.Write([]byte(content))
+	return tmpfile.Name()
+}
+
+func readTempYamlFile(name string) string {
+	content, _ := ioutil.ReadFile(name)
+	return string(content)
+}
+
+func removeTempYamlFile(name string) {
+	_ = os.Remove(name)
+}

yaml.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -15,30 +16,45 @@ import (
 var trimOutput = true
 var writeInplace = false
 var writeScript = ""
-var inputJSON = false
 var outputToJSON = false
 var verbose = false
 var log = logging.MustGetLogger("yaml")
+
+func main() {
+	cmd := newCommandCLI()
+	if err := cmd.Execute(); err != nil {
+		fmt.Println(err.Error())
+		os.Exit(1)
+	}
+}
+
+func newCommandCLI() *cobra.Command {
+	var rootCmd = &cobra.Command{
+		Use: "yaml",
+		PersistentPreRun: func(cmd *cobra.Command, args []string) {
 			var format = logging.MustStringFormatter(
 				`%{color}%{time:15:04:05} %{shortfunc} [%{level:.4s}]%{color:reset} %{message}`,
 			)
 			var backend = logging.AddModuleLevel(
 				logging.NewBackendFormatter(logging.NewLogBackend(os.Stderr, "", 0), format))
 
-func main() {
+			if verbose {
+				backend.SetLevel(logging.DEBUG, "")
+			} else {
 				backend.SetLevel(logging.ERROR, "")
+			}
+
 			logging.SetBackend(backend)
+		},
+	}
 
-	var cmdRead = createReadCmd()
-	var cmdWrite = createWriteCmd()
-	var cmdNew = createNewCmd()
-
-	var rootCmd = &cobra.Command{Use: "yaml"}
 	rootCmd.PersistentFlags().BoolVarP(&trimOutput, "trim", "t", true, "trim yaml output")
 	rootCmd.PersistentFlags().BoolVarP(&outputToJSON, "tojson", "j", false, "output as json")
 	rootCmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "verbose mode")
-	rootCmd.AddCommand(cmdRead, cmdWrite, cmdNew)
+
-	_ = rootCmd.Execute()
+	rootCmd.AddCommand(createReadCmd(), createWriteCmd(), createNewCmd())
+
+	return rootCmd
 }
 
 func createReadCmd() *cobra.Command {
@@ -54,7 +70,7 @@ yaml r things.yaml a.array[0].blah
 yaml r things.yaml a.array[*].blah
       `,
 		Long: "Outputs the value of the given path in the yaml file to STDOUT",
-		Run:  readProperty,
+		RunE: readProperty,
 	}
 }
 
@@ -81,7 +97,7 @@ a.b.c: true,
 a.b.e:
   - name: bob
 `,
-		Run: writeProperty,
+		RunE: writeProperty,
 	}
 	cmdWrite.PersistentFlags().BoolVarP(&writeInplace, "inplace", "i", false, "update the yaml file inplace")
 	cmdWrite.PersistentFlags().StringVarP(&writeScript, "script", "s", "", "yaml script for updating yaml")
@@ -104,37 +120,47 @@ Outputs to STDOUT
 Create Scripts:
 Note that you can give a create script to perform more sophisticated yaml. This follows the same format as the update script.
 `,
-		Run: newProperty,
+		RunE: newProperty,
 	}
 	cmdNew.PersistentFlags().StringVarP(&writeScript, "script", "s", "", "yaml script for updating yaml")
 	return cmdNew
 }
 
-func readProperty(cmd *cobra.Command, args []string) {
+func readProperty(cmd *cobra.Command, args []string) error {
-	if verbose {
+	data, err := read(args)
-		backend.SetLevel(logging.DEBUG, "")
+	if err != nil {
+		return err
 	}
-	print(read(args))
+	dataStr, err := toString(data)
+	if err != nil {
+		return err
+	}
+	cmd.Println(dataStr)
+	return nil
 }
 
-func read(args []string) interface{} {
+func read(args []string) (interface{}, error) {
-
 	var parsedData yaml.MapSlice
 	var path = ""
-	if len(args) > 1 {
+
+	if len(args) < 1 {
+		return nil, errors.New("Must provide filename")
+	} else if len(args) > 1 {
 		path = args[1]
 	}
-	err := readData(args[0], &parsedData, inputJSON)
+
-	if err != nil {
+	if err := readData(args[0], &parsedData); err != nil {
 		var generalData interface{}
-		readDataOrDie(args[0], &generalData, inputJSON)
+		if err = readData(args[0], &generalData); err != nil {
+			return nil, err
+		}
 		item := yaml.MapItem{Key: "thing", Value: generalData}
 		parsedData = yaml.MapSlice{item}
 		path = "thing." + path
 	}
 
 	if path == "" {
-		return parsedData
+		return parsedData, nil
 	}
 
 	var paths = parsePath(path)
@@ -142,20 +168,27 @@ func read(args []string) interface{} {
 	return readMap(parsedData, paths[0], paths[1:])
 }
 
-func newProperty(cmd *cobra.Command, args []string) {
+func newProperty(cmd *cobra.Command, args []string) error {
-	if verbose {
+	updatedData, err := newYaml(args)
-		backend.SetLevel(logging.DEBUG, "")
+	if err != nil {
+		return err
 	}
-	updatedData := newYaml(args)
+	dataStr, err := toString(updatedData)
-	print(updatedData)
+	if err != nil {
+		return err
+	}
+	cmd.Println(dataStr)
+	return nil
 }
 
-func newYaml(args []string) interface{} {
+func newYaml(args []string) (interface{}, error) {
 	var writeCommands yaml.MapSlice
 	if writeScript != "" {
-		readDataOrDie(writeScript, &writeCommands, false)
+		if err := readData(writeScript, &writeCommands); err != nil {
+			return nil, err
+		}
 	} else if len(args) < 2 {
-		die("Must provide <path_to_update> <value>")
+		return nil, errors.New("Must provide <path_to_update> <value>")
 	} else {
 		writeCommands = make(yaml.MapSlice, 1)
 		writeCommands[0] = yaml.MapItem{Key: args[0], Value: parseValue(args[1])}
@@ -175,19 +208,31 @@ func newYaml(args []string) interface{} {
 	return updateParsedData(parsedData, writeCommands, prependCommand)
 }
 
-func writeProperty(cmd *cobra.Command, args []string) {
+func writeProperty(cmd *cobra.Command, args []string) error {
-	if verbose {
+	updatedData, err := updateYaml(args)
-		backend.SetLevel(logging.DEBUG, "")
+	if err != nil {
-	}
+		return err
-	updatedData := updateYaml(args)
-	if writeInplace {
-		_ = ioutil.WriteFile(args[0], []byte(yamlToString(updatedData)), 0644)
-	} else {
-		print(updatedData)
 	}
+	return write(cmd, args[0], updatedData)
 }
 
-func updateParsedData(parsedData yaml.MapSlice, writeCommands yaml.MapSlice, prependCommand string) interface{} {
+func write(cmd *cobra.Command, filename string, updatedData interface{}) error {
+	if writeInplace {
+		dataStr, err := yamlToString(updatedData)
+		if err != nil {
+			return err
+		}
+		return ioutil.WriteFile(filename, []byte(dataStr), 0644)
+	}
+	dataStr, err := toString(updatedData)
+	if err != nil {
+		return err
+	}
+	cmd.Println(dataStr)
+	return nil
+}
+
+func updateParsedData(parsedData yaml.MapSlice, writeCommands yaml.MapSlice, prependCommand string) (interface{}, error) {
 	var prefix = ""
 	if prependCommand != "" {
 		prefix = prependCommand + "."
@@ -201,26 +246,29 @@ func updateParsedData(parsedData yaml.MapSlice, writeCommands yaml.MapSlice, pre
 	if prependCommand != "" {
 		return readMap(parsedData, prependCommand, make([]string, 0))
 	}
-	return parsedData
+	return parsedData, nil
 }
 
-func updateYaml(args []string) interface{} {
+func updateYaml(args []string) (interface{}, error) {
 	var writeCommands yaml.MapSlice
 	var prependCommand = ""
 	if writeScript != "" {
-		readDataOrDie(writeScript, &writeCommands, false)
+		if err := readData(writeScript, &writeCommands); err != nil {
+			return nil, err
+		}
 	} else if len(args) < 3 {
-		die("Must provide <filename> <path_to_update> <value>")
+		return nil, errors.New("Must provide <filename> <path_to_update> <value>")
 	} else {
 		writeCommands = make(yaml.MapSlice, 1)
 		writeCommands[0] = yaml.MapItem{Key: args[1], Value: parseValue(args[2])}
 	}
 
 	var parsedData yaml.MapSlice
-	err := readData(args[0], &parsedData, inputJSON)
+	if err := readData(args[0], &parsedData); err != nil {
-	if err != nil {
 		var generalData interface{}
-		readDataOrDie(args[0], &generalData, inputJSON)
+		if err = readData(args[0], &generalData); err != nil {
+			return nil, err
+		}
 		item := yaml.MapItem{Key: "thing", Value: generalData}
 		parsedData = yaml.MapSlice{item}
 		prependCommand = "thing"
@@ -246,69 +294,43 @@ func parseValue(argument string) interface{} {
 	return argument[1 : len(argument)-1]
 }
 
-func print(context interface{}) {
+func toString(context interface{}) (string, error) {
-	var out string
 	if outputToJSON {
-		out = jsonToString(context)
+		return jsonToString(context)
-	} else {
-		out = yamlToString(context)
 	}
-	fmt.Println(out)
+	return yamlToString(context)
 }
 
-func yamlToString(context interface{}) string {
+func yamlToString(context interface{}) (string, error) {
 	out, err := yaml.Marshal(context)
 	if err != nil {
-		die("error printing yaml: %v", err)
+		return "", fmt.Errorf("error printing yaml: %v", err)
 	}
 	outStr := string(out)
 	// trim the trailing new line as it's easier for a script to add
 	// it in if required than to remove it
 	if trimOutput {
-		return strings.Trim(outStr, "\n ")
+		return strings.Trim(outStr, "\n "), nil
 	}
-	return outStr
+	return outStr, nil
 }
 
-func readDataOrDie(filename string, parsedData interface{}, readAsJSON bool) {
+func readData(filename string, parsedData interface{}) error {
-	err := readData(filename, parsedData, readAsJSON)
-	if err != nil {
-		die("error parsing data: ", err)
-	}
-}
-
-func readData(filename string, parsedData interface{}, readAsJSON bool) error {
 	if filename == "" {
-		die("Must provide filename")
+		return errors.New("Must provide filename")
 	}
 
 	var rawData []byte
+	var err error
 	if filename == "-" {
-		rawData = readStdin()
+		rawData, err = ioutil.ReadAll(os.Stdin)
 	} else {
-		rawData = readFile(filename)
+		rawData, err = ioutil.ReadFile(filename)
+	}
+
+	if err != nil {
+		return err
 	}
 
 	return yaml.Unmarshal(rawData, parsedData)
 }
-
-func readStdin() []byte {
-	bytes, err := ioutil.ReadAll(os.Stdin)
-	if err != nil {
-		die("error reading stdin", err)
-	}
-	return bytes
-}
-
-func readFile(filename string) []byte {
-	var rawData, readError = ioutil.ReadFile(filename)
-	if readError != nil {
-		die("error: %v", readError)
-	}
-	return rawData
-}
-
-func die(message ...interface{}) {
-	fmt.Println(message)
-	os.Exit(1)
-}

yaml_test.go

@@ -24,23 +24,23 @@ func TestParseValue(t *testing.T) {
 }
 
 func TestRead(t *testing.T) {
-	result := read([]string{"examples/sample.yaml", "b.c"})
+	result, _ := read([]string{"examples/sample.yaml", "b.c"})
 	assertResult(t, 2, result)
 }
 
 func TestReadArray(t *testing.T) {
-	result := read([]string{"examples/sample_array.yaml", "[1]"})
+	result, _ := read([]string{"examples/sample_array.yaml", "[1]"})
 	assertResult(t, 2, result)
 }
 
 func TestReadString(t *testing.T) {
-	result := read([]string{"examples/sample_text.yaml"})
+	result, _ := read([]string{"examples/sample_text.yaml"})
 	assertResult(t, "hi", result)
 }
 
 func TestOrder(t *testing.T) {
-	result := read([]string{"examples/order.yaml"})
+	result, _ := read([]string{"examples/order.yaml"})
-	formattedResult := yamlToString(result)
+	formattedResult, _ := yamlToString(result)
 	assertResult(t,
 		`version: 3
 application: MyApp`,
@@ -48,7 +48,7 @@ application: MyApp`,
 }
 
 func TestNewYaml(t *testing.T) {
-	result := newYaml([]string{"b.c", "3"})
+	result, _ := newYaml([]string{"b.c", "3"})
 	formattedResult := fmt.Sprintf("%v", result)
 	assertResult(t,
 		"[{b [{c 3}]}]",
@@ -56,7 +56,7 @@ func TestNewYaml(t *testing.T) {
 }
 
 func TestNewYamlArray(t *testing.T) {
-	result := newYaml([]string{"[0].cat", "meow"})
+	result, _ := newYaml([]string{"[0].cat", "meow"})
 	formattedResult := fmt.Sprintf("%v", result)
 	assertResult(t,
 		"[[{cat meow}]]",
@@ -64,7 +64,7 @@ func TestNewYamlArray(t *testing.T) {
 }
 
 func TestUpdateYaml(t *testing.T) {
-	result := updateYaml([]string{"examples/sample.yaml", "b.c", "3"})
+	result, _ := updateYaml([]string{"examples/sample.yaml", "b.c", "3"})
 	formattedResult := fmt.Sprintf("%v", result)
 	assertResult(t,
 		"[{a Easy! as one two three} {b [{c 3} {d [3 4]} {e [[{name fred} {value 3}] [{name sam} {value 4}]]}]}]",
@@ -72,7 +72,7 @@ func TestUpdateYaml(t *testing.T) {
 }
 
 func TestUpdateYamlArray(t *testing.T) {
-	result := updateYaml([]string{"examples/sample_array.yaml", "[0]", "3"})
+	result, _ := updateYaml([]string{"examples/sample_array.yaml", "[0]", "3"})
 	formattedResult := fmt.Sprintf("%v", result)
 	assertResult(t,
 		"[3 2 3]",
@@ -81,7 +81,17 @@ func TestUpdateYamlArray(t *testing.T) {
 
 func TestUpdateYaml_WithScript(t *testing.T) {
 	writeScript = "examples/instruction_sample.yaml"
-	updateYaml([]string{"examples/sample.yaml"})
+	_, _ = updateYaml([]string{"examples/sample.yaml"})
+}
+
+func TestUpdateYaml_WithUnknownScript(t *testing.T) {
+	writeScript = "fake-unknown"
+	_, err := updateYaml([]string{"examples/sample.yaml"})
+	if err == nil {
+		t.Error("Expected error due to unknown file")
+	}
+	expectedOutput := `open fake-unknown: no such file or directory`
+	assertResult(t, expectedOutput, err.Error())
 }
 
 func TestNewYaml_WithScript(t *testing.T) {
@@ -90,7 +100,17 @@ func TestNewYaml_WithScript(t *testing.T) {
   c: cat
   e:
   - name: Mike Farah`
-	result := newYaml([]string{""})
+	result, _ := newYaml([]string{""})
-	actualResult := yamlToString(result)
+	actualResult, _ := yamlToString(result)
 	assertResult(t, expectedResult, actualResult)
 }
+
+func TestNewYaml_WithUnknownScript(t *testing.T) {
+	writeScript = "fake-unknown"
+	_, err := newYaml([]string{""})
+	if err == nil {
+		t.Error("Expected error due to unknown file")
+	}
+	expectedOutput := `open fake-unknown: no such file or directory`
+	assertResult(t, expectedOutput, err.Error())
+}