engine: add output format support

Makefile

@@ -16,7 +16,7 @@ YAMLFMT_BIN ?= $(shell pwd)/dist/yamlfmt
 .PHONY: integrationtest
 integrationtest:
 	$(MAKE) build
-	go test -tags=integration_test ./integrationtest/command
+	go test -v -tags=integration_test ./integrationtest/command
 
 .PHONY: integrationtest_v
 integrationtest_v:
@@ -28,11 +28,19 @@ integrationtest_stdout:
 	$(MAKE) build
 	go test -v -tags=integration_test ./integrationtest/command -stdout
 
-.PHONY: integrationtest_local_update
+.PHONY: integrationtest_update
 integrationtest_update:
 	$(MAKE) build
 	go test -tags=integration_test ./integrationtest/command -update
 
+.PHONY: command_test_case
+command_test_case:
+ifndef TESTNAME
+	$(error "TESTNAME undefined")
+endif
+	mkdir -p integrationtest/command/testdata/$(TESTNAME)/before && \
+	mkdir -p integrationtest/command/testdata/$(TESTNAME)/stdout
+
 .PHONY: install
 install:
 	go install ./cmd/yamlfmt

cmd/yamlfmt/config.go

@@ -220,7 +220,7 @@ func validatePath(path string) error {
 }
 
 func makeCommandConfigFromData(configData map[string]any) (*command.Config, error) {
-	config := command.NewConfig()
+	config := command.Config{FormatterConfig: command.NewFormatterConfig()}
 	err := mapstructure.Decode(configData, &config)
 	if err != nil {
 		return nil, err
@@ -253,23 +253,23 @@ func makeCommandConfigFromData(configData map[string]any) (*command.Config, erro
 		config.Extensions = []string{"yaml", "yml"}
 	}
 
-	// Default to doublestar flag if not set in config
+	// Apply the general rule that the config takes precedence over
+	// the command line flags.
 	if !config.Doublestar {
 		config.Doublestar = *flagDoublestar
 	}
-
-	// Default to continue_on_error flag if not set in config
 	if !config.ContinueOnError {
 		config.ContinueOnError = *flagContinueOnError
 	}
-
 	if !config.GitignoreExcludes {
 		config.GitignoreExcludes = *flagGitignoreExcludes
 	}
-
 	if config.GitignorePath == "" {
 		config.GitignorePath = *flagGitignorePath
 	}
+	if config.OutputFormat == "" {
+		config.OutputFormat = getOutputFormatFromFlag()
+	}
 
 	// Overwrite config if includes are provided through args
 	if len(flag.Args()) > 0 {

cmd/yamlfmt/flags.go

@@ -20,7 +20,8 @@ import (
 	"runtime"
 	"strings"
 
-	"github.com/google/yamlfmt/command"
+	"github.com/google/yamlfmt"
+	"github.com/google/yamlfmt/engine"
 )
 
 var (
@@ -38,6 +39,7 @@ operation without performing it.`)
 	flagContinueOnError   *bool   = flag.Bool("continue_on_error", false, "Continue to format files that didn't fail instead of exiting with code 1.")
 	flagGitignoreExcludes *bool   = flag.Bool("gitignore_excludes", false, "Use a gitignore file for excludes")
 	flagGitignorePath     *string = flag.String("gitignore_path", ".gitignore", "Path to gitignore file to use")
+	flagOutputFormat      *string = flag.String("output_format", "default", "The engine output format")
 	flagExclude                   = arrayFlag{}
 	flagFormatter                 = arrayFlag{}
 	flagExtensions                = arrayFlag{}
@@ -85,17 +87,21 @@ func configureHelp() {
 	}
 }
 
-func getOperationFromFlag() command.Operation {
+func getOperationFromFlag() yamlfmt.Operation {
 	if *flagIn || isStdinArg() {
-		return command.OperationStdin
+		return yamlfmt.OperationStdin
 	}
 	if *flagLint {
-		return command.OperationLint
+		return yamlfmt.OperationLint
 	}
 	if *flagDry {
-		return command.OperationDry
+		return yamlfmt.OperationDry
 	}
-	return command.OperationFormat
+	return yamlfmt.OperationFormat
+}
+
+func getOutputFormatFromFlag() engine.EngineOutputFormat {
+	return engine.EngineOutputFormat(*flagOutputFormat)
 }
 
 func isStdinArg() bool {

cmd/yamlfmt/main.go

@@ -18,6 +18,7 @@ import (
 	"flag"
 	"fmt"
 	"log"
+	"os"
 
 	"github.com/google/yamlfmt"
 	"github.com/google/yamlfmt/command"
@@ -29,7 +30,8 @@ var version string = "0.11.0"
 
 func main() {
 	if err := run(); err != nil {
-		log.Fatal(err)
+		l := log.New(os.Stderr, "", 0)
+		l.Fatal(err)
 	}
 }
 

command/command.go

@@ -19,53 +19,38 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"log"
 	"os"
 
 	"github.com/google/yamlfmt"
 	"github.com/google/yamlfmt/engine"
 )
 
-type Operation int
-
-const (
-	OperationFormat Operation = iota
-	OperationLint
-	OperationDry
-	OperationStdin
-)
-
 type FormatterConfig struct {
 	Type              string         `mapstructure:"type"`
 	FormatterSettings map[string]any `mapstructure:",remain"`
 }
 
 // NewFormatterConfig returns an empty formatter config with all fields initialized.
-func NewFormatterConfig() FormatterConfig {
-	return FormatterConfig{FormatterSettings: make(map[string]any)}
+func NewFormatterConfig() *FormatterConfig {
+	return &FormatterConfig{FormatterSettings: make(map[string]any)}
 }
 
 type Config struct {
-	Extensions        []string               `mapstructure:"extensions"`
-	Include           []string               `mapstructure:"include"`
-	Exclude           []string               `mapstructure:"exclude"`
-	RegexExclude      []string               `mapstructure:"regex_exclude"`
-	FormatterConfig   *FormatterConfig       `mapstructure:"formatter,omitempty"`
-	Doublestar        bool                   `mapstructure:"doublestar"`
-	ContinueOnError   bool                   `mapstructure:"continue_on_error"`
-	LineEnding        yamlfmt.LineBreakStyle `mapstructure:"line_ending"`
-	GitignoreExcludes bool                   `mapstructure:"gitignore_excludes"`
-	GitignorePath     string                 `mapstructure:"gitignore_path"`
-}
-
-// NewConfig returns an empty config with all fields initialized.
-func NewConfig() Config {
-	formatterConfig := NewFormatterConfig()
-	return Config{FormatterConfig: &formatterConfig}
+	Extensions        []string                  `mapstructure:"extensions"`
+	Include           []string                  `mapstructure:"include"`
+	Exclude           []string                  `mapstructure:"exclude"`
+	RegexExclude      []string                  `mapstructure:"regex_exclude"`
+	FormatterConfig   *FormatterConfig          `mapstructure:"formatter,omitempty"`
+	Doublestar        bool                      `mapstructure:"doublestar"`
+	ContinueOnError   bool                      `mapstructure:"continue_on_error"`
+	LineEnding        yamlfmt.LineBreakStyle    `mapstructure:"line_ending"`
+	GitignoreExcludes bool                      `mapstructure:"gitignore_excludes"`
+	GitignorePath     string                    `mapstructure:"gitignore_path"`
+	OutputFormat      engine.EngineOutputFormat `mapstructure:"output_format"`
 }
 
 type Command struct {
-	Operation Operation
+	Operation yamlfmt.Operation
 	Registry  *yamlfmt.Registry
 	Config    *Config
 	Quiet     bool
@@ -113,6 +98,7 @@ func (c *Command) Run() error {
 		Formatter:        formatter,
 		Quiet:            c.Quiet,
 		ContinueOnError:  c.Config.ContinueOnError,
+		OutputFormat:     c.Config.OutputFormat,
 	}
 
 	collectedPaths, err := c.collectPaths()
@@ -129,17 +115,20 @@ func (c *Command) Run() error {
 
 	paths, err := c.analyzePaths(collectedPaths)
 	if err != nil {
-		log.Printf("path analysis found the following errors:\n%v", err)
-		log.Println("Continuing...")
+		fmt.Printf("path analysis found the following errors:\n%v", err)
+		fmt.Println("Continuing...")
 	}
 
 	switch c.Operation {
-	case OperationFormat:
-		err := eng.Format(paths)
+	case yamlfmt.OperationFormat:
+		out, err := eng.Format(paths)
+		if out != nil {
+			fmt.Print(out)
+		}
 		if err != nil {
 			return err
 		}
-	case OperationLint:
+	case yamlfmt.OperationLint:
 		out, err := eng.Lint(paths)
 		if err != nil {
 			return err
@@ -150,17 +139,17 @@ func (c *Command) Run() error {
 			// component of the lint functionality.
 			return errors.New(out.String())
 		}
-	case OperationDry:
+	case yamlfmt.OperationDry:
 		out, err := eng.DryRun(paths)
 		if err != nil {
 			return err
 		}
-		if out.Message == "" && out.Files.ChangedCount() == 0 {
-			log.Print("No files will be changed.")
+		if out != nil {
+			fmt.Print(out)
 		} else {
-			log.Print(out)
+			fmt.Print("No files will be changed.")
 		}
-	case OperationStdin:
+	case yamlfmt.OperationStdin:
 		stdinYaml, err := readFromStdin()
 		if err != nil {
 			return err
@@ -169,7 +158,7 @@ func (c *Command) Run() error {
 		if err != nil {
 			return err
 		}
-		fmt.Print(string(out))
+		fmt.Print(out)
 	}
 
 	return nil

docs/command-usage.md

@@ -74,18 +74,19 @@ These flags will configure the underlying behaviour of the command.
 
 The string array flags can be a bit confusing. See the [String Array Flags](#string-array-flags) section for more information.
 
-| Name                  | Flag                  | Type     | Example                                                   | Description |
-|:----------------------|:----------------------|:---------|:----------------------------------------------------------|:------------|
-| Config File Path      | `-conf`               | string   | `yamlfmt -conf ./config/.yamlfmt`                         | Specify a path to read a [configuration file](./config-file.md) from. |
-| Global Config         | `-global_conf`        | bool     | `yamlfmt -global_conf`                                    | Force yamlfmt to use the configuration file from the system config directory. |
-| Disable Global Config | `-no_global_conf`     | bool     | `yamlfmt -no_global_conf`                                 | Disable looking for the configuration file from the system config directory. |
-| Doublestar            | `-dstar`              | bool     | `yamlfmt -dstar "**/*.yaml"`                              | Enable [Doublestar](./paths.md#doublestar) path collection mode. Note that doublestar patterns should be specified with quotes in bash to prevent shell expansion. |
-| Exclude               | `-exclude`            | []string | `yamlfmt -exclude ./not/,these_paths.yaml`                | Patterns to exclude from path collection. These are in addition to the exclude patterns specified in the [config file](./config-file.md) |
-| Gitignore Excludes    | `-gitignore_excludes` | bool     | `yamlfmt -gitignore_excludes`                             | Use a gitignore file to exclude paths. This is in addition to otherwise specified exclude patterns. |
-| Gitignore Path        | `-gitignore_path`     | string   | `yamlfmt -gitignore_path .special_gitignore`              | Specify a path to a gitignore file to use. Defaults to `.gitignore` (in working directory). |
-| Extensions            | `-extensions`         | []string | `yamlfmt -extensions yaml,yml`                            | Extensions to use in standard path collection. Has no effect in Doublestar mode. These add to extensions specified in the [config file](./config-file.md)
-| Formatter Config      | `-formatter`          | []string | `yamlfmt -formatter indent=2,include_document_start=true` | Provide configuration values for the formatter. See [Formatter Configuration Options](./config-file.md#basic-formatter) for options. Each field is specified as `configkey=value`. |
-| Debug Logging         | `-debug`              | []string | `yamlfmt -debug paths,config`                             | Enable debug logging. See [Debug Logging](#debug-logging) for more information. |
+| Name                  | Flag                  | Type              | Example                                                   | Description |
+|:----------------------|:----------------------|:------------------|:----------------------------------------------------------|:------------|
+| Config File Path      | `-conf`               | string            | `yamlfmt -conf ./config/.yamlfmt`                         | Specify a path to read a [configuration file](./config-file.md) from. |
+| Global Config         | `-global_conf`        | bool              | `yamlfmt -global_conf`                                    | Force yamlfmt to use the configuration file from the system config directory. |
+| Disable Global Config | `-no_global_conf`     | bool              | `yamlfmt -no_global_conf`                                 | Disable looking for the configuration file from the system config directory. |
+| Doublestar            | `-dstar`              | bool              | `yamlfmt -dstar "**/*.yaml"`                              | Enable [Doublestar](./paths.md#doublestar) path collection mode. Note that doublestar patterns should be specified with quotes in bash to prevent shell expansion. |
+| Exclude               | `-exclude`            | []string          | `yamlfmt -exclude ./not/,these_paths.yaml`                | Patterns to exclude from path collection. These are in addition to the exclude patterns specified in the [config file](./config-file.md) |
+| Gitignore Excludes    | `-gitignore_excludes` | bool              | `yamlfmt -gitignore_excludes`                             | Use a gitignore file to exclude paths. This is in addition to otherwise specified exclude patterns. |
+| Gitignore Path        | `-gitignore_path`     | string            | `yamlfmt -gitignore_path .special_gitignore`              | Specify a path to a gitignore file to use. Defaults to `.gitignore` (in working directory). |
+| Extensions            | `-extensions`         | []string          | `yamlfmt -extensions yaml,yml`                            | Extensions to use in standard path collection. Has no effect in Doublestar mode. These add to extensions specified in the [config file](./config-file.md)
+| Formatter Config      | `-formatter`          | []string          | `yamlfmt -formatter indent=2,include_document_start=true` | Provide configuration values for the formatter. See [Formatter Configuration Options](./config-file.md#basic-formatter) for options. Each field is specified as `configkey=value`. |
+| Debug Logging         | `-debug`              | []string          | `yamlfmt -debug paths,config`                             | Enable debug logging. See [Debug Logging](#debug-logging) for more information. |
+| Output Format         | `-output_format`      | `default`, `line` | `yamlfmt -output_format line`                             | Choose a different output format. Defaults to `default`. See [Output docs](./output.md) for more information. |
 
 #### String Array Flags
 

docs/config-file.md

@@ -35,15 +35,16 @@ The command package defines the main command engine that `cmd/yamlfmt` uses. It
 | Key                      | Type           | Default      | Description |
 |:-------------------------|:---------------|:-------------|:------------|
 | `line_ending`            | `lf` or `crlf` | `crlf` on Windows, `lf` otherwise | Parse and write the file with "lf" or "crlf" line endings. This global setting will override any formatter `line_ending` options. |
-| `doublestar`             | bool           | false         | Use [doublestar](https://github.com/bmatcuk/doublestar) for include and exclude paths. (This was the default before 0.7.0) |
-| `continue_on_error`      | bool           | false         | Continue formatting and don't exit with code 1 when there is an invalid yaml file found. |
-| `include`                | []string       | []            | The paths for the command to include for formatting. See [Specifying Paths][] for more details. |
-| `exclude`                | []string       | []            | The paths for the command to exclude from formatting. See [Specifying Paths][] for more details. |
-| `gitignore_excludes`     | bool           | false         | Use gitignore files for exclude paths. This is in addition to the patterns from the `exclude` option. |
-| `gitignore_path`         | string         | `.gitignore`  | The path to the gitignore file to use. |
-| `regex_exclude`          | []string       | []            | Regex patterns to match file contents for, if the file content matches the regex the file will be excluded. Use [Golang regexes](https://regex101.com/). |
-| `extensions`             | []string       | []            | The extensions to use for standard mode path collection. See [Specifying Paths][] for more details. |
-| `formatter`              | map[string]any | `type: basic` | Formatter settings. See [Formatter](#formatter) for more details. |
+| `doublestar`             | bool                | false         | Use [doublestar](https://github.com/bmatcuk/doublestar) for include and exclude paths. (This was the default before 0.7.0) |
+| `continue_on_error`      | bool                | false         | Continue formatting and don't exit with code 1 when there is an invalid yaml file found. |
+| `include`                | []string            | []            | The paths for the command to include for formatting. See [Specifying Paths][] for more details. |
+| `exclude`                | []string            | []            | The paths for the command to exclude from formatting. See [Specifying Paths][] for more details. |
+| `gitignore_excludes`     | bool                | false         | Use gitignore files for exclude paths. This is in addition to the patterns from the `exclude` option. |
+| `gitignore_path`         | string              | `.gitignore`  | The path to the gitignore file to use. |
+| `regex_exclude`          | []string            | []            | Regex patterns to match file contents for, if the file content matches the regex the file will be excluded. Use [Golang regexes](https://regex101.com/). |
+| `extensions`             | []string            | []            | The extensions to use for standard mode path collection. See [Specifying Paths][] for more details. |
+| `formatter`              | map[string]any      | `type: basic` | Formatter settings. See [Formatter](#formatter) for more details. |
+| `output_format`          | `default` or `line` | `default`     | The output format to use. See [Output docs](./output.md) for more details. |
 
 ## Formatter
 

docs/output.md

@@ -0,0 +1,34 @@
+# Output
+
+The tool supports different output formats when writing to stdout/stderr. This can be configured through either a command line flag `-output_format` or through the `output_format` configuration field in the [config file](./config-file.md).
+
+The following values are supported:
+
+## `default`
+
+Example:
+```
+The following formatting differences were found:
+
+y.yaml:
+  a:     a:
+-  b: 1    b: 1
++
+z.yaml:
+  a:     a:
+-  b: 1    b: 1
++
+x.yaml:
+  a:     a:
+-  b: 1    b: 1
++
+```
+
+## `line`
+
+Example:
+```
+x.yaml: formatting difference found
+y.yaml: formatting difference found
+z.yaml: formatting difference found
+```