Change lib list --updatable output to be clearer if no lib is updatable

cli/lib/list.go

@@ -109,6 +109,9 @@ func (ir installedResult) Data() interface{} {
 
 func (ir installedResult) String() string {
 	if ir.installedLibs == nil || len(ir.installedLibs) == 0 {
+		if listFlags.updatable {
+			return "No updates available."
+		}
 		return "No libraries installed."
 	}
 	sort.Slice(ir.installedLibs, func(i, j int) bool {

test/test_lib.py

@@ -236,3 +236,50 @@ def test_search_paragraph(run_command):
     assert result.ok
     libs_json = json.loads(result.stdout)
     assert 1 == len(libs_json.get("libraries"))
+
+
+def test_lib_list_with_updatable_flag(run_command):
+    # Init the environment explicitly
+    run_command("lib update-index")
+
+    # No libraries to update
+    result = run_command("lib list --updatable")
+    assert result.ok
+    assert "" == result.stderr
+    assert "No updates available." == result.stdout.strip()
+    # No library to update in json
+    result = run_command("lib list --updatable --format json")
+    assert result.ok
+    assert "" == result.stderr
+    assert 0 == len(json.loads(result.stdout))
+
+    # Install outdated library
+    assert run_command("lib install [email protected]")
+    # Install latest version of library
+    assert run_command("lib install WiFi101")
+
+    res = run_command("lib list --updatable")
+    assert res.ok
+    assert "" == res.stderr
+    # lines = res.stdout.strip().splitlines()
+    lines = [l.strip().split(maxsplit=4) for l in res.stdout.strip().splitlines()]
+    assert 2 == len(lines)
+    assert ["Name", "Installed", "Available", "Location", "Description"] in lines
+    line = lines[1]
+    assert "ArduinoJson" == line[0]
+    assert "6.11.0" == line[1]
+    # Verifies available version is not equal to installed one and not empty
+    assert "6.11.0" != line[2]
+    assert "" != line[2]
+    assert "An efficient and elegant JSON library..." == line[4]
+
+    # Look at the JSON output
+    res = run_command("lib list --updatable --format json")
+    assert res.ok
+    assert "" == res.stderr
+    data = json.loads(res.stdout)
+    assert 1 == len(data)
+    # be sure data contains the available version
+    assert "6.11.0" == data[0]["library"]["version"]
+    assert "6.11.0" != data[0]["release"]["version"]
+    assert "" != data[0]["release"]["version"]