Add check for stray sketches in library

check/checkconfigurations/checkconfigurations.go

@@ -926,6 +926,21 @@ var configurations = []Type{
 		ErrorModes:      nil,
 		CheckFunction:   checkfunctions.LibraryHasExe,
 	},
+	{
+		ProjectType:     projecttype.Library,
+		Category:        "structure",
+		Subcategory:     "",
+		ID:              "",
+		Brief:           "stray sketch",
+		Description:     "",
+		MessageTemplate: "Sketch(es) found outside examples and extras folders: {{.}}. See: https://arduino.github.io/arduino-cli/latest/library-specification/#library-examples",
+		DisableModes:    nil,
+		EnableModes:     []checkmode.Type{checkmode.All},
+		InfoModes:       nil,
+		WarningModes:    []checkmode.Type{checkmode.Permissive},
+		ErrorModes:      []checkmode.Type{checkmode.Default},
+		CheckFunction:   checkfunctions.LibraryHasStraySketches,
+	},
 	{
 		ProjectType:     projecttype.Library,
 		Category:        "structure",

check/checkfunctions/library.go

@@ -29,6 +29,7 @@ import (
 	"github.com/arduino/arduino-check/check/checkresult"
 	"github.com/arduino/arduino-check/configuration"
 	"github.com/arduino/arduino-check/project/library"
+	"github.com/arduino/arduino-check/project/sketch"
 	"github.com/arduino/arduino-cli/arduino/libraries"
 	"github.com/arduino/arduino-cli/arduino/utils"
 	"github.com/arduino/go-properties-orderedmap"
@@ -990,6 +991,45 @@ func LibraryHasExe() (result checkresult.Type, output string) {
 	return checkresult.Pass, ""
 }
 
+// LibraryHasStraySketches checks for sketches outside the `examples` and `extras` folders.
+func LibraryHasStraySketches() (result checkresult.Type, output string) {
+	straySketchPaths := []string{}
+	if sketch.ContainsMainSketchFile(checkdata.ProjectPath()) { // Check library root.
+		straySketchPaths = append(straySketchPaths, checkdata.ProjectPath().String())
+	}
+
+	// Check subfolders.
+	projectPathListing, err := checkdata.ProjectPath().ReadDir()
+	if err != nil {
+		panic(err)
+	}
+	projectPathListing.FilterDirs()
+
+	for _, topLevelSubfolder := range projectPathListing {
+		if topLevelSubfolder.Base() == "examples" || topLevelSubfolder.Base() == "extras" {
+			continue // Skip valid sketch locations.
+		}
+
+		topLevelSubfolderRecursiveListing, err := topLevelSubfolder.ReadDirRecursive()
+		if err != nil {
+			panic(err)
+		}
+		topLevelSubfolderRecursiveListing.FilterDirs()
+
+		for _, subfolder := range topLevelSubfolderRecursiveListing {
+			if sketch.ContainsMainSketchFile(subfolder) {
+				straySketchPaths = append(straySketchPaths, subfolder.String())
+			}
+		}
+	}
+
+	if len(straySketchPaths) > 0 {
+		return checkresult.Fail, strings.Join(straySketchPaths, ", ")
+	}
+
+	return checkresult.Pass, ""
+}
+
 // ProhibitedCharactersInLibraryFolderName checks for prohibited characters in the library folder name.
 func ProhibitedCharactersInLibraryFolderName() (result checkresult.Type, output string) {
 	if !validProjectPathBaseName(checkdata.ProjectPath().Base()) {

check/checkfunctions/library_test.go

@@ -292,6 +292,18 @@ func TestLibraryHasExe(t *testing.T) {
 
 	checkLibraryCheckFunction(LibraryHasExe, testTables, t)
 }
+
+func TestLibraryHasStraySketches(t *testing.T) {
+	testTables := []libraryCheckFunctionTestTable{
+		{"Sketch in root", "SketchInRoot", checkresult.Fail, ""},
+		{"Sketch in subfolder", "MisspelledExamplesFolder", checkresult.Fail, ""},
+		{"Sketch in legit location", "ExamplesFolder", checkresult.Pass, ""},
+		{"No sketches", "Recursive", checkresult.Pass, ""},
+	}
+
+	checkLibraryCheckFunction(LibraryHasStraySketches, testTables, t)
+}
+
 func TestProhibitedCharactersInLibraryFolderName(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Has prohibited characters", "Prohibited CharactersInFolderName", checkresult.Fail, ""},

check/checkfunctions/testdata/libraries/SketchInRoot/Example.ino

@@ -0,0 +1,2 @@
+void setup() {}
+void loop() {}

check/checkfunctions/testdata/libraries/SketchInRoot/library.properties

@@ -0,0 +1,9 @@
+name=SketchInRoot
+version=1.0.0
+author=Cristian Maglie <c.maglie@example.com>, Pippo Pluto <pippo@example.com>
+maintainer=Cristian Maglie <c.maglie@example.com>
+sentence=A library that makes coding a web server a breeze.
+paragraph=Supports HTTP1.1 and you can do GET and POST.
+category=Communication
+url=http://example.com/
+architectures=avr

project/sketch/sketch.go

@@ -20,6 +20,8 @@ See: https://arduino.github.io/arduino-cli/latest/sketch-specification/
 package sketch
 
 import (
+	"fmt"
+
 	"github.com/arduino/arduino-cli/arduino/globals"
 	"github.com/arduino/go-paths-helper"
 )
@@ -31,6 +33,30 @@ func HasMainFileValidExtension(filePath *paths.Path) bool {
 	return hasMainFileValidExtension
 }
 
+// ContainsMainSketchFile checks whether the provided path contains a file with valid main sketch file extension.
+func ContainsMainSketchFile(searchPath *paths.Path) bool {
+	if searchPath.NotExist() {
+		panic(fmt.Sprintf("Error: provided path %s does not exist.", searchPath))
+	}
+	if searchPath.IsNotDir() {
+		panic(fmt.Sprintf("Error: provided path %s is not a directory.", searchPath))
+	}
+
+	directoryListing, err := searchPath.ReadDir()
+	if err != nil {
+		panic(err)
+	}
+
+	directoryListing.FilterOutDirs()
+	for _, potentialHeaderFile := range directoryListing {
+		if HasMainFileValidExtension(potentialHeaderFile) {
+			return true
+		}
+	}
+
+	return false
+}
+
 // HasSupportedExtension returns whether the file at the given path has any of the file extensions supported for source/header files of a sketch.
 func HasSupportedExtension(filePath *paths.Path) bool {
 	_, hasAdditionalFileValidExtensions := globals.AdditionalFileValidExtensions[filePath.Ext()]

project/sketch/sketch_test.go

@@ -16,17 +16,30 @@
 package sketch
 
 import (
+	"os"
 	"testing"
 
 	"github.com/arduino/go-paths-helper"
 	"github.com/stretchr/testify/assert"
 )
 
+var testDataPath *paths.Path
+
+func init() {
+	workingDirectory, _ := os.Getwd()
+	testDataPath = paths.New(workingDirectory, "testdata")
+}
+
 func TestHasMainFileValidExtension(t *testing.T) {
 	assert.True(t, HasMainFileValidExtension(paths.New("/foo/bar.ino")))
 	assert.False(t, HasMainFileValidExtension(paths.New("/foo/bar.h")))
 }
 
+func TestContainsMainSketchFile(t *testing.T) {
+	assert.True(t, ContainsMainSketchFile(testDataPath.Join("Valid")))
+	assert.False(t, ContainsMainSketchFile(testDataPath.Join("ContainsNoMainSketchFile")))
+}
+
 func TestHasSupportedExtension(t *testing.T) {
 	assert.True(t, HasSupportedExtension(paths.New("/foo/bar.ino")))
 	assert.True(t, HasSupportedExtension(paths.New("/foo/bar.h")))

project/sketch/testdata/Valid/Valid.ino

@@ -0,0 +1,2 @@
+void setup() {}
+void loop() {}