kconfig: tests: check visibility of tristate choice values in y choice

If tristate choice values depend on symbols set to 'm', they should be
hidden when the choice containing them is changed from 'm' to 'y'
(i.e. exclusive choice).

This issue was fixed by commit fa64e5f6 ("kconfig/symbol.c: handle
choice_values that depend on 'm' symbols").

Add a test case to avoid regression.

For the input in this unit test, there is a room for argument if
"# CONFIG_CHOICE1 is not set" should be written to the .config file.

After commit fa64e5f6, this line was written to the .config file.

With commit cb67ab2c ("kconfig: do not write choice values when
their dependency becomes n"), it is not written now.

In this test, "# CONFIG_CHOICE1 is not set" is don't care.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>

scripts/kconfig/tests/choice_value_with_m_dep/Kconfig

+config MODULES
+	def_bool y
+	option modules
+
+config DEP
+	tristate
+	default m
+
+choice
+	prompt "Tristate Choice"
+
+config CHOICE0
+	tristate "Choice 0"
+
+config CHOICE1
+	tristate "Choice 1"
+	depends on DEP
+
+endchoice

scripts/kconfig/tests/choice_value_with_m_dep/__init__.py

+"""
+Hide tristate choice values with mod dependency in y choice.
+
+If tristate choice values depend on symbols set to 'm', they should be
+hidden when the choice containing them is changed from 'm' to 'y'
+(i.e. exclusive choice).
+
+Related Linux commit: fa64e5f6a35efd5e77d639125d973077ca506074
+"""
+
+
+def test(conf):
+    assert conf.oldaskconfig('config', 'y') == 0
+    assert conf.config_contains('expected_config')
+    assert conf.stdout_contains('expected_stdout')

scripts/kconfig/tests/choice_value_with_m_dep/config

+CONFIG_CHOICE0=m
+CONFIG_CHOICE1=m

scripts/kconfig/tests/choice_value_with_m_dep/expected_config

+CONFIG_MODULES=y
+CONFIG_DEP=m
+CONFIG_CHOICE0=y

scripts/kconfig/tests/choice_value_with_m_dep/expected_stdout

+Tristate Choice [M/y/?] y
+Tristate Choice
+> 1. Choice 0 (CHOICE0)
+choice[1]: 1