tests/test_bareboxdriver.py: Add barebox boot test

Add 'test_barebox_boot' test to meet code coverage
and maintain related documentation

Signed-off-by: Fabian Meuren <f.meuren@phytec.de>
[bst: moved boot_name documentation to commit introducing it, moved
optional boot name argument to dedicated commit, adapted test for
loglevel changes]
Signed-off-by: Bastian Krause <bst@pengutronix.de>

Author: meuren

tests/test_bareboxdriver.py

@@ -41,3 +41,16 @@ def test_barebox_run_error(self, target_with_fakeconsole, mocker):
             res = d.run_check("test")
         res = d.run("test")
         assert res == (['error'], [], 1)
+
+    def test_barebox_boot(self, target_with_fakeconsole, mocker):
+        t = target_with_fakeconsole
+        d = BareboxDriver(t, "barebox", boot_command='boot -v foo')
+        d = t.get_driver(BareboxDriver, activate=False)
+        # mock for d._run('echo $global.loglevel')
+        d._run = mocker.MagicMock(return_value=(['7'], [], 0))
+        t.activate(d)
+        d._run = mocker.MagicMock(return_value=(['success'], [], 0))
+        d.boot()
+        assert d.console.txq.pop() == b"boot -v foo\n"
+        d.boot(name='bar')
+        assert d.console.txq.pop() == b"boot -v bar\n"