kunit: test: add assertion printing library

Add `struct kunit_assert` and friends which provide a structured way to
capture data from an expectation or an assertion (introduced later in
the series) so that it may be printed out in the event of a failure.
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

lib/kunit/Makefile

 obj-$(CONFIG_KUNIT) +=			test.o \
-					string-stream.o
+					string-stream.o \
+					assert.o

lib/kunit/assert.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Assertion and expectation serialization API.
+ *
+ * Copyright (C) 2019, Google LLC.
+ * Author: Brendan Higgins <brendanhiggins@google.com>
+ */
+#include <kunit/assert.h>
+
+void kunit_base_assert_format(const struct kunit_assert *assert,
+			      struct string_stream *stream)
+{
+	const char *expect_or_assert = NULL;
+
+	switch (assert->type) {
+	case KUNIT_EXPECTATION:
+		expect_or_assert = "EXPECTATION";
+		break;
+	case KUNIT_ASSERTION:
+		expect_or_assert = "ASSERTION";
+		break;
+	}
+
+	string_stream_add(stream, "%s FAILED at %s:%d\n",
+			 expect_or_assert, assert->file, assert->line);
+}
+
+void kunit_assert_print_msg(const struct kunit_assert *assert,
+			    struct string_stream *stream)
+{
+	if (assert->message.fmt)
+		string_stream_add(stream, "\n%pV", &assert->message);
+}
+
+void kunit_fail_assert_format(const struct kunit_assert *assert,
+			      struct string_stream *stream)
+{
+	kunit_base_assert_format(assert, stream);
+	string_stream_add(stream, "%pV", &assert->message);
+}
+
+void kunit_unary_assert_format(const struct kunit_assert *assert,
+			       struct string_stream *stream)
+{
+	struct kunit_unary_assert *unary_assert = container_of(
+			assert, struct kunit_unary_assert, assert);
+
+	kunit_base_assert_format(assert, stream);
+	if (unary_assert->expected_true)
+		string_stream_add(stream,
+				 "\tExpected %s to be true, but is false\n",
+				 unary_assert->condition);
+	else
+		string_stream_add(stream,
+				 "\tExpected %s to be false, but is true\n",
+				 unary_assert->condition);
+	kunit_assert_print_msg(assert, stream);
+}
+
+void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
+				     struct string_stream *stream)
+{
+	struct kunit_ptr_not_err_assert *ptr_assert = container_of(
+			assert, struct kunit_ptr_not_err_assert, assert);
+
+	kunit_base_assert_format(assert, stream);
+	if (!ptr_assert->value) {
+		string_stream_add(stream,
+				 "\tExpected %s is not null, but is\n",
+				 ptr_assert->text);
+	} else if (IS_ERR(ptr_assert->value)) {
+		string_stream_add(stream,
+				 "\tExpected %s is not error, but is: %ld\n",
+				 ptr_assert->text,
+				 PTR_ERR(ptr_assert->value));
+	}
+	kunit_assert_print_msg(assert, stream);
+}
+
+void kunit_binary_assert_format(const struct kunit_assert *assert,
+				struct string_stream *stream)
+{
+	struct kunit_binary_assert *binary_assert = container_of(
+			assert, struct kunit_binary_assert, assert);
+
+	kunit_base_assert_format(assert, stream);
+	string_stream_add(stream,
+			 "\tExpected %s %s %s, but\n",
+			 binary_assert->left_text,
+			 binary_assert->operation,
+			 binary_assert->right_text);
+	string_stream_add(stream, "\t\t%s == %lld\n",
+			 binary_assert->left_text,
+			 binary_assert->left_value);
+	string_stream_add(stream, "\t\t%s == %lld",
+			 binary_assert->right_text,
+			 binary_assert->right_value);
+	kunit_assert_print_msg(assert, stream);
+}
+
+void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
+				    struct string_stream *stream)
+{
+	struct kunit_binary_ptr_assert *binary_assert = container_of(
+			assert, struct kunit_binary_ptr_assert, assert);
+
+	kunit_base_assert_format(assert, stream);
+	string_stream_add(stream,
+			 "\tExpected %s %s %s, but\n",
+			 binary_assert->left_text,
+			 binary_assert->operation,
+			 binary_assert->right_text);
+	string_stream_add(stream, "\t\t%s == %pK\n",
+			 binary_assert->left_text,
+			 binary_assert->left_value);
+	string_stream_add(stream, "\t\t%s == %pK",
+			 binary_assert->right_text,
+			 binary_assert->right_value);
+	kunit_assert_print_msg(assert, stream);
+}
+
+void kunit_binary_str_assert_format(const struct kunit_assert *assert,
+				    struct string_stream *stream)
+{
+	struct kunit_binary_str_assert *binary_assert = container_of(
+			assert, struct kunit_binary_str_assert, assert);
+
+	kunit_base_assert_format(assert, stream);
+	string_stream_add(stream,
+			 "\tExpected %s %s %s, but\n",
+			 binary_assert->left_text,
+			 binary_assert->operation,
+			 binary_assert->right_text);
+	string_stream_add(stream, "\t\t%s == %s\n",
+			 binary_assert->left_text,
+			 binary_assert->left_value);
+	string_stream_add(stream, "\t\t%s == %s",
+			 binary_assert->right_text,
+			 binary_assert->right_value);
+	kunit_assert_print_msg(assert, stream);
+}