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From:   Richard Fitzgerald <rf@opensource.cirrus.com>
To:     <brendan.higgins@linux.dev>, <davidgow@google.com>,
        <rmoar@google.com>
CC:     <linux-kselftest@vger.kernel.org>, <kunit-dev@googlegroups.com>,
        <linux-kernel@vger.kernel.org>, <patches@opensource.cirrus.com>,
        Richard Fitzgerald <rf@opensource.cirrus.com>
Subject: [PATCH v4 03/10] kunit: string-stream: Add cases for adding empty strings to a string_stream
Date:   Mon, 14 Aug 2023 14:23:02 +0100
Message-ID: <20230814132309.32641-4-rf@opensource.cirrus.com>
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Adds string_stream_append_empty_string_test() to test that adding an
empty string to a string_stream doesn't create a new empty fragment.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
 lib/kunit/string-stream-test.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/lib/kunit/string-stream-test.c b/lib/kunit/string-stream-test.c
index 1d46d5f06d2a..efe13e3322b5 100644
--- a/lib/kunit/string-stream-test.c
+++ b/lib/kunit/string-stream-test.c
@@ -206,11 +206,32 @@ static void string_stream_append_test(struct kunit *test)
 	KUNIT_EXPECT_STREQ(test, string_stream_get_string(stream_1), stream_2_content);
 }
 
+/* Adding an empty string should not create a fragment. */
+static void string_stream_append_empty_string_test(struct kunit *test)
+{
+	struct string_stream *stream;
+
+	stream = alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
+
+	/* Formatted empty string */
+	string_stream_add(stream, "%s", "");
+	KUNIT_EXPECT_TRUE(test, string_stream_is_empty(stream));
+	KUNIT_EXPECT_TRUE(test, list_empty(&stream->fragments));
+
+	/* Adding an empty string to a non-empty stream */
+	string_stream_add(stream, "Add this line");
+	string_stream_add(stream, "%s", "");
+	KUNIT_EXPECT_EQ(test, list_count_nodes(&stream->fragments), 1);
+	KUNIT_EXPECT_STREQ(test, string_stream_get_string(stream), "Add this line");
+}
+
 static struct kunit_case string_stream_test_cases[] = {
 	KUNIT_CASE(string_stream_init_test),
 	KUNIT_CASE(string_stream_line_add_test),
 	KUNIT_CASE(string_stream_variable_length_line_test),
 	KUNIT_CASE(string_stream_append_test),
+	KUNIT_CASE(string_stream_append_empty_string_test),
 	{}
 };
 
-- 
2.30.2