Add --quiet flag to suppress per-file formatting status output (#603)

Summary:
## Changes

- **`ParsedArgs`**: Added `quiet: Boolean` field; added `--quiet` to the argument parser and help text
- **`Main.format()`**: Gate the `"Done formatting $fileName"` stderr print behind `!args.quiet`; error messages are always emitted regardless of the flag

## Usage

```sh
ktfmt --quiet src/**/*.kt   # formats files silently; errors still reported to stderr
```

Closes #558.

Pull Request resolved: #603

Reviewed By: cortinico

Differential Revision: D95993436

Pulled By: hick209

fbshipit-source-id: bc2f0fdee9d0ebcef74c32ad1776637d31f8f5cc

Author: Goooler

CHANGELOG.md

@@ -12,7 +12,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
 ## [Unreleased]
 ### Added
+
 - Support `ij_kotlin_continuation_indent_size` in editorconfig.
+- Add `--quiet` flag to suppress per-file formatting status output.
 
 ### Fixed
 - Backtick-escaped full-path imports are no longer incorrectly removed as unused (https://github.com/facebook/ktfmt/issues/532)

core/src/main/java/com/facebook/ktfmt/cli/Main.kt

@@ -170,7 +170,9 @@ class Main(
         if (!alreadyFormatted) {
           file.writeText(formattedCode, UTF_8)
         }
-        err.println("Done formatting $fileName")
+        if (!args.quiet) {
+          err.println("Done formatting $fileName")
+        }
       }
 
       return alreadyFormatted

core/src/main/java/com/facebook/ktfmt/cli/ParsedArgs.kt

@@ -37,6 +37,8 @@ data class ParsedArgs(
     /** File name to report when formating code from stdin */
     val stdinName: String?,
     val editorConfig: Boolean,
+    /** Suppress all non-error output. */
+    val quiet: Boolean,
 ) {
   companion object {
 
@@ -84,6 +86,7 @@ data class ParsedArgs(
         |  --do-not-remove-unused-imports    Leaves all imports in place, even if not used
         |  --enable-editorconfig             Enable .editorconfig overrides for supported formatting options (limited)
         |                                        see https://github.com/facebook/ktfmt/blob/main/README.md
+        |  --quiet                           Suppress all non-error output
         |  
         |ARGFILE:
         |  If the only argument begins with '@', the remainder of the argument is treated
@@ -110,6 +113,7 @@ data class ParsedArgs(
       var removeUnusedImports = true
       var stdinName: String? = null
       var editorConfig = false
+      var quiet = false
 
       if ("--help" in args || "-h" in args) return ParseResult.ShowMessage(HELP_TEXT)
       if ("--version" in args || "-v" in args) {
@@ -125,6 +129,7 @@ data class ParsedArgs(
           arg == "--set-exit-if-changed" -> setExitIfChanged = true
           arg == "--do-not-remove-unused-imports" -> removeUnusedImports = false
           arg == "--enable-editorconfig" -> editorConfig = true
+          arg == "--quiet" -> quiet = true
           arg.startsWith("--stdin-name=") ->
               stdinName =
                   parseKeyValueArg("--stdin-name", arg)
@@ -158,6 +163,7 @@ data class ParsedArgs(
               setExitIfChanged,
               stdinName,
               editorConfig,
+              quiet,
           )
       )
     }

core/src/test/java/com/facebook/ktfmt/cli/MainTest.kt

@@ -538,4 +538,27 @@ class MainTest {
 
     assertThat(exitCode).isEqualTo(0)
   }
+
+  @Test
+  fun `--quiet suppresses 'Done formatting' output`() {
+    val code = """fun f () =    println( "hello, world" )"""
+    val file = root.resolve("foo.kt")
+    file.writeText(code, UTF_8)
+
+    Main(emptyInput, PrintStream(out), PrintStream(err), arrayOf("--quiet", file.toString())).run()
+
+    assertThat(err.toString(testCharset)).doesNotContain("Done formatting")
+  }
+
+  @Test
+  fun `--quiet still reports errors`() {
+    val fooBar = root.resolve("foo.kt")
+    fooBar.writeText("fun    f1 (  ", UTF_8)
+    val returnValue =
+        Main(emptyInput, PrintStream(out), PrintStream(err), arrayOf("--quiet", fooBar.toString()))
+            .run()
+
+    assertThat(returnValue).isEqualTo(1)
+    assertThat(err.toString(testCharset)).contains("foo.kt:1:14: error: ")
+  }
 }

core/src/test/java/com/facebook/ktfmt/cli/ParsedArgsTest.kt

@@ -109,6 +109,12 @@ class ParsedArgsTest {
     assertThat(parsed.editorConfig).isEqualTo(true)
   }
 
+  @Test
+  fun `parseOptions recognizes --quiet`() {
+    val parsed = assertSucceeds(ParsedArgs.parseOptions(arrayOf("--quiet", "foo.kt")))
+    assertThat(parsed.quiet).isTrue()
+  }
+
   @Test
   fun `parseOptions recognizes --stdin-name`() {
     val parsed = assertSucceeds(ParsedArgs.parseOptions(arrayOf("--stdin-name=my/foo.kt", "-")))
@@ -251,6 +257,7 @@ class ParsedArgsTest {
       removedUnusedImports: Boolean = true,
       stdinName: String? = null,
       editorConfig: Boolean = false,
+      quiet: Boolean = false,
   ): ParseResult.Ok {
     val returnedFormattingOptions =
         formattingOptions.copy(removeUnusedImports = removedUnusedImports)
@@ -262,6 +269,7 @@ class ParsedArgsTest {
             setExitIfChanged,
             stdinName,
             editorConfig,
+            quiet,
         )
     )
   }