arduino
diff --git a/‎arduino/libraries/libraries_test.go
Copy file name to clipboardExpand all lines: arduino/libraries/libraries_test.go
+11Lines changed: 11 additions & 0 deletions b/‎arduino/libraries/libraries_test.go
Copy file name to clipboardExpand all lines: arduino/libraries/libraries_test.go
+11Lines changed: 11 additions & 0 deletions
diff --git a/‎arduino/libraries/loader.go
Copy file name to clipboardExpand all lines: arduino/libraries/loader.go
+22Lines changed: 22 additions & 0 deletions b/‎arduino/libraries/loader.go
Copy file name to clipboardExpand all lines: arduino/libraries/loader.go
+22Lines changed: 22 additions & 0 deletions
diff --git a/‎arduino/libraries/testdata/LegacyLib/LegacyLib.h
Copy file name to clipboardExpand all lines: arduino/libraries/testdata/LegacyLib/LegacyLib.h b/‎arduino/libraries/testdata/LegacyLib/LegacyLib.h
Copy file name to clipboardExpand all lines: arduino/libraries/testdata/LegacyLib/LegacyLib.h
diff --git a/‎docs/library-specification.md
Copy file name to clipboardExpand all lines: docs/library-specification.md
+3-3Lines changed: 3 additions & 3 deletions b/‎docs/library-specification.md
Copy file name to clipboardExpand all lines: docs/library-specification.md
+3-3Lines changed: 3 additions & 3 deletions
diff --git a/‎internal/integrationtest/lib/lib_test.go
Copy file name to clipboardExpand all lines: internal/integrationtest/lib/lib_test.go
+37Lines changed: 37 additions & 0 deletions b/‎internal/integrationtest/lib/lib_test.go
Copy file name to clipboardExpand all lines: internal/integrationtest/lib/lib_test.go
+37Lines changed: 37 additions & 0 deletions
@@ -73,4 +73,15 @@ func TestLibrariesLoader(t *testing.T) {
 		require.Equal(t, "LibWithNonUTF8Properties", lib.Name)
 		require.Equal(t, "àrduìnò", lib.Author)
 	}
+	{
+		lib, err := Load(paths.New("testdata", "EmptyLib"), User)
+		require.Error(t, err)
+		require.Nil(t, lib)
+	}
+	{
+		lib, err := Load(paths.New("testdata", "LegacyLib"), User)
+		require.NoError(t, err)
+		require.Equal(t, "LegacyLib", lib.Name)
+		require.True(t, lib.IsLegacy)
+	}
 }
@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/arduino/arduino-cli/arduino/globals"
 	"github.com/arduino/arduino-cli/arduino/sketch"
 	"github.com/arduino/go-paths-helper"
 	properties "github.com/arduino/go-properties-orderedmap"
@@ -126,6 +127,11 @@ func makeNewLibrary(libraryDir *paths.Path, location LibraryLocation) (*Library,
 }
 
 func makeLegacyLibrary(path *paths.Path, location LibraryLocation) (*Library, error) {
+	if foundHeader, err := containsHeaderFile(path); err != nil {
+		return nil, err
+	} else if !foundHeader {
+		return nil, errors.Errorf(tr("invalid library: no header files found"))
+	}
 	library := &Library{
 		InstallDir:    path.Canonical(),
 		Location:      location,
@@ -186,3 +192,19 @@ func addExamplesToPathList(examplesPath *paths.Path, list *paths.PathList) error
 	}
 	return nil
 }
+
+// containsHeaderFile returns true if the directory contains a ".h" file.
+// Returns false otherwise
+func containsHeaderFile(d *paths.Path) (bool, error) {
+	dirContent, err := d.ReadDir()
+	if err != nil {
+		return false, fmt.Errorf(tr("reading directory %[1]s content: %[2]w", d, err))
+	}
+	dirContent.FilterOutDirs()
+	headerExtensions := []string{}
+	for k := range globals.HeaderFilesValidExtensions {
+		headerExtensions = append(headerExtensions, k)
+	}
+	dirContent.FilterSuffix(headerExtensions...)
+	return len(dirContent) > 0, nil
+}
@@ -419,6 +419,6 @@ allowing the compilation to fail in a difficult to understand way):
 ## Old library format (pre-1.5)
 
 In order to support old libraries (from Arduino IDE 1.0.x), Arduino IDE and Arduino CLI will also compile libraries
-missing a library.properties metadata file. As a result, these libraries should behave as they did in Arduino IDE 1.0.x,
-although they will be available for all boards, including non-AVR ones (which wouldn’t have been present in Arduino IDE
-1.0.x).
+missing a library.properties metadata file (the header file is still required). As a result, these libraries should
+behave as they did in Arduino IDE 1.0.x, although they will be available for all boards, including non-AVR ones (which
+wouldn’t have been present in Arduino IDE 1.0.x).
@@ -1587,3 +1587,40 @@ func TestLibBundlesWhenLibWithTheSameNameIsInstalledGlobally(t *testing.T) {
 		requirejson.Parse(t, stdout).Query(`.[].library.examples[1]`).MustContain(`"OTALeds"`)
 	}
 }
+
+func TestLibListDoesNotIncludeEmptyLibraries(t *testing.T) {
+	env, cli := integrationtest.CreateArduinoCLIWithEnvironment(t)
+	defer env.CleanUp()
+
+	_, _, err := cli.Run("lib", "update-index")
+	require.NoError(t, err)
+
+	// Create a library that does not have neither a library.properties nor a ".h" file
+	emptyLib := cli.SketchbookDir().Join("libraries", "empty")
+	require.NoError(t, emptyLib.MkdirAll())
+
+	// Check that the output of lib list and lib examples is empty
+	stdout, _, err := cli.Run("lib", "list", "--format", "json")
+	require.NoError(t, err)
+	requirejson.Empty(t, stdout)
+
+	stdout, _, err = cli.Run("lib", "examples", "--format", "json")
+	require.NoError(t, err)
+	requirejson.Empty(t, stdout)
+
+	// Create a library with a header
+	libWithHeader := cli.SketchbookDir().Join("libraries", "libWithHeader")
+	require.NoError(t, libWithHeader.MkdirAll())
+	f, err := libWithHeader.Join("libWithHeader.h").Create()
+	require.NoError(t, err)
+	require.NoError(t, f.Close())
+
+	// Check that the output of lib list and lib examples contains the library
+	stdout, _, err = cli.Run("lib", "list", "--format", "json")
+	require.NoError(t, err)
+	requirejson.Len(t, stdout, 1)
+
+	stdout, _, err = cli.Run("lib", "examples", "--format", "json")
+	require.NoError(t, err)
+	requirejson.Len(t, stdout, 1)
+}