Added more help info about using write with an update script

Added more tests to avoid bugs ;)

README.md

@@ -150,7 +150,7 @@ b.e[0].name: Howdy Partner
 then
 
 ```bash
-yaml -w -s update_instructions.yaml sample.yaml
+yaml w -s update_instructions.yaml sample.yaml
 ```
 will output:
 ```yaml

precheckin.sh

@@ -3,12 +3,12 @@
 gofmt -w .
 golint
 go test
+go build
 
 # acceptance test
-go build
-X=$(./yaml r sample.yaml b.c)
+X=$(./yaml w sample.yaml b.c 3 | ./yaml r - b.c)
 
-if [ $X != 2 ]
+if [ $X != 3 ]
   then
 	echo "Failed acceptance test: expected 2 but was $X"
   exit 1

yaml.go

@@ -33,14 +33,25 @@ yaml r things.yaml a.array[*].blah
 	var cmdWrite = &cobra.Command{
 		Use:     "write [yaml_file] [path] [value]",
 		Aliases: []string{"w"},
-		Short:   "yaml w [--inplace/-i] sample.yaml a.b.c newValueForC",
+		Short:   "yaml w [--inplace/-i] [--script/-s script_file] sample.yaml a.b.c newValueForC",
 		Example: `
 yaml write things.yaml a.b.c cat
 yaml write --inplace things.yaml a.b.c cat
 yaml w -i things.yaml a.b.c cat
+yaml w --script update_script.yaml things.yaml
+yaml w -i -s update_script.yaml things.yaml
 			`,
 		Long: `Updates the yaml file w.r.t the given path and value.
-Outputs to STDOUT unless the inplace flag is used, in which case the file is updated instead.`,
+Outputs to STDOUT unless the inplace flag is used, in which case the file is updated instead.
+
+Update Scripts:
+Note that you can give an update script to perform more sophisticated updated. Update script
+format is a yaml map where the key is the path and the value is..well the value. e.g.:
+---
+a.b.c: true,
+a.b.e:
+  - name: bob
+`,
 		Run: writeProperty,
 	}
 	cmdWrite.PersistentFlags().BoolVarP(&writeInplace, "inplace", "i", false, "update the yaml file inplace")
@@ -53,27 +64,40 @@ Outputs to STDOUT unless the inplace flag is used, in which case the file is upd
 }
 
 func readProperty(cmd *cobra.Command, args []string) {
+	printYaml(read(args))
+}
+
+func read(args []string) interface{} {
 	var parsedData map[interface{}]interface{}
 
 	readYaml(args[0], &parsedData)
 
 	if len(args) == 1 {
-		printYaml(parsedData)
-		os.Exit(0)
+		return parsedData
 	}
 
 	var paths = parsePath(args[1])
 
-	printYaml(readMap(parsedData, paths[0], paths[1:len(paths)]))
+	return readMap(parsedData, paths[0], paths[1:len(paths)])
 }
 
 func writeProperty(cmd *cobra.Command, args []string) {
+	updatedData := updateYaml(args)
+	if writeInplace {
+		ioutil.WriteFile(args[0], []byte(yamlToString(updatedData)), 0644)
+	} else {
+		printYaml(updatedData)
+	}
+}
+
+func updateYaml(args []string) interface{} {
 	var writeCommands map[string]interface{}
 	if writeScript != "" {
 		readYaml(writeScript, &writeCommands)
 	} else if len(args) < 3 {
 		die("Must provide <filename> <path_to_update> <value>")
 	} else {
+		writeCommands = make(map[string]interface{})
 		writeCommands[args[1]] = parseValue(args[2])
 	}
 
@@ -84,13 +108,9 @@ func writeProperty(cmd *cobra.Command, args []string) {
 		var paths = parsePath(path)
 		write(parsedData, paths[0], paths[1:len(paths)], value)
 	}
-
-	if writeInplace {
-		ioutil.WriteFile(args[0], []byte(yamlToString(parsedData)), 0644)
-	} else {
-		printYaml(parsedData)
-	}
+	return parsedData
 }
+
 func parseValue(argument string) interface{} {
 	var value, err interface{}
 	var inQuotes = argument[0] == '"'

yaml_test.go

@@ -20,3 +20,17 @@ func TestParseValue(t *testing.T) {
 		assertResultWithContext(t, tt.expectedResult, parseValue(tt.argument), tt.testDescription)
 	}
 }
+
+func TestRead(t *testing.T) {
+	result := read([]string{"sample.yaml", "b.c"})
+	assertResult(t, 2, result)
+}
+
+func TestUpdateYaml(t *testing.T) {
+	updateYaml([]string{"sample.yaml", "b.c", "3"})
+}
+
+func TestUpdateYaml_WithScript(t *testing.T) {
+	writeScript = "instruction_sample.yaml"
+	updateYaml([]string{"sample.yaml"})
+}