Tests: Establish root Tests directory, move Userland/Tests there

With the goal of centralizing all tests in the system, this is a
first step to establish a Tests sub-tree. It will contain all of
the unit tests and test harnesses for the various components in the
system.

1 files changed, 143 insertions, 0 deletions

diff --git a/Tests/LibC/snprintf-correctness.cpp b/Tests/LibC/snprintf-correctness.cpp
new file mode 100644
index 0000000000..0df2a5cc30
--- /dev/null
+++ b/Tests/LibC/snprintf-correctness.cpp
@@ -0,0 +1,143 @@
+/*
+ * Copyright (c) 2020, Ben Wiederhake <BenWiederhake.GitHub@gmx.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/TestCase.h>
+
+#include <AK/ByteBuffer.h>
+#include <AK/Random.h>
+#include <AK/StringBuilder.h>
+#include <ctype.h>
+#include <stdio.h>
+
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
+
+struct Testcase {
+    const char* dest;
+    size_t dest_n;
+    const char* fmt;
+    const char* arg;
+    int expected_return;
+    const char* dest_expected;
+    size_t dest_expected_n; // == dest_n
+};
+
+static String show(const ByteBuffer& buf)
+{
+    StringBuilder builder;
+    for (size_t i = 0; i < buf.size(); ++i) {
+        builder.appendff("{:02x}", buf[i]);
+    }
+    builder.append(' ');
+    builder.append('(');
+    for (size_t i = 0; i < buf.size(); ++i) {
+        if (isprint(buf[i]))
+            builder.append(buf[i]);
+        else
+            builder.append('_');
+    }
+    builder.append(')');
+    return builder.build();
+}
+
+static const size_t SANDBOX_CANARY_SIZE = 8;
+
+static bool test_single(const Testcase& testcase)
+{
+    // Preconditions:
+    if (testcase.dest_n != testcase.dest_expected_n) {
+        warnln("dest length {} != expected dest length {}? Check testcase! (Probably miscounted.)", testcase.dest_n, testcase.dest_expected_n);
+        return false;
+    }
+
+    // Setup
+    ByteBuffer actual = ByteBuffer::create_uninitialized(SANDBOX_CANARY_SIZE + testcase.dest_n + SANDBOX_CANARY_SIZE);
+    fill_with_random(actual.data(), actual.size());
+    ByteBuffer expected = actual.isolated_copy();
+    VERIFY(actual.offset_pointer(0) != expected.offset_pointer(0));
+    actual.overwrite(SANDBOX_CANARY_SIZE, testcase.dest, testcase.dest_n);
+    expected.overwrite(SANDBOX_CANARY_SIZE, testcase.dest_expected, testcase.dest_expected_n);
+    // "unsigned char" != "char", so we have to convince the compiler to allow this.
+    char* dst = reinterpret_cast<char*>(actual.offset_pointer(SANDBOX_CANARY_SIZE));
+
+    // The actual call:
+    int actual_return = snprintf(dst, testcase.dest_n, testcase.fmt, testcase.arg);
+
+    // Checking the results:
+    bool return_ok = actual_return == testcase.expected_return;
+    bool canary_1_ok = actual.slice(0, SANDBOX_CANARY_SIZE) == expected.slice(0, SANDBOX_CANARY_SIZE);
+    bool main_ok = actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n) == expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n);
+    bool canary_2_ok = actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE) == expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE);
+    bool buf_ok = actual == expected;
+
+    // Evaluate gravity:
+    if (buf_ok && (!canary_1_ok || !main_ok || !canary_2_ok)) {
+        warnln("Internal error! ({} != {} | {} | {})", buf_ok, canary_1_ok, main_ok, canary_2_ok);
+        buf_ok = false;
+    }
+    if (!canary_1_ok) {
+        warnln("Canary 1 overwritten: Expected {}\n"
+               "                   instead got {}",
+            show(expected.slice(0, SANDBOX_CANARY_SIZE)),
+            show(actual.slice(0, SANDBOX_CANARY_SIZE)));
+    }
+    if (!main_ok) {
+        warnln("Wrong output: Expected {}\n"
+               "          instead, got {}",
+            show(expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n)),
+            show(actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n)));
+    }
+    if (!canary_2_ok) {
+        warnln("Canary 2 overwritten: Expected {}\n"
+               "                  instead, got {}",
+            show(expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE)),
+            show(actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE)));
+    }
+    if (!return_ok) {
+        warnln("Wrong return value: Expected {}, got {} instead!", testcase.expected_return, actual_return);
+    }
+
+    return buf_ok && return_ok;
+}
+
+// Drop the NUL terminator added by the C++ compiler.
+#define LITERAL(x) x, (sizeof(x) - 1)
+
+static const char* const POISON = (const char*)1;
+
+TEST_CASE(golden_path)
+{
+    EXPECT(test_single({ LITERAL("Hello World!\0\0\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend!\0\0") }));
+    EXPECT(test_single({ LITERAL("Hello World!\0\0\0"), "Hello %s!", "Friend", 13, LITERAL("Hello Friend!\0\0") }));
+    EXPECT(test_single({ LITERAL("aaaaaaaaaa"), "whf", POISON, 3, LITERAL("whf\0aaaaaa") }));
+    EXPECT(test_single({ LITERAL("aaaaaaaaaa"), "w%sf", "h", 3, LITERAL("whf\0aaaaaa") }));
+}
+
+TEST_CASE(border_cases)
+{
+    EXPECT(test_single({ LITERAL("Hello World!\0\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend!\0") }));
+    EXPECT(test_single({ LITERAL("AAAA"), "whf", POISON, 3, LITERAL("whf\0") }));
+    EXPECT(test_single({ LITERAL("AAAA"), "%s", "whf", 3, LITERAL("whf\0") }));
+}
+
+TEST_CASE(too_long)
+{
+    EXPECT(test_single({ LITERAL("Hello World!\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend\0") }));
+    EXPECT(test_single({ LITERAL("Hello World!\0"), "This source is %s too long!", "just *way*", 35, LITERAL("This source \0") }));
+    EXPECT(test_single({ LITERAL("x"), "This source is %s too long!", "just *way*", 35, LITERAL("\0") }));
+}
+
+TEST_CASE(special_cases)
+{
+    EXPECT(test_single({ LITERAL(""), "Hello Friend!", POISON, 13, LITERAL("") }));
+    EXPECT_EQ(snprintf(nullptr, 0, "Hello, friend!"), 14);
+    EXPECT(test_single({ LITERAL(""), "", POISON, 0, LITERAL("") }));
+    EXPECT(test_single({ LITERAL("x"), "", POISON, 0, LITERAL("\0") }));
+    EXPECT(test_single({ LITERAL("xx"), "", POISON, 0, LITERAL("\0x") }));
+    EXPECT(test_single({ LITERAL("xxx"), "", POISON, 0, LITERAL("\0xx") }));
+    EXPECT(test_single({ LITERAL(""), "whf", POISON, 3, LITERAL("") }));
+    EXPECT(test_single({ LITERAL("x"), "whf", POISON, 3, LITERAL("\0") }));
+    EXPECT(test_single({ LITERAL("xx"), "whf", POISON, 3, LITERAL("w\0") }));
+}