Add iswalpha tests

Author: Prabhuk

libc/config/baremetal/riscv/entrypoints.txt

@@ -278,6 +278,9 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.wchar.wcslen
     libc.src.wchar.wctob
 
+    # wctype.h entrypoints
+    libc.src.wctype.iswalpha
+
     # internal entrypoints
     libc.startup.baremetal.init
     libc.startup.baremetal.fini

libc/test/src/CMakeLists.txt

@@ -70,6 +70,7 @@ add_subdirectory(stdlib)
 add_subdirectory(string)
 add_subdirectory(strings)
 add_subdirectory(wchar)
+add_subdirectory(wctype)
 add_subdirectory(time)
 add_subdirectory(unistd)
 

libc/test/src/wctype/CMakeLists.txt

@@ -0,0 +1,11 @@
+add_custom_target(libc_wctype_unittests)
+
+add_libc_test(
+  iswalpha_test
+  SUITE
+    libc_wctype_unittests
+  SRCS
+    iswalpha_test.cpp
+  DEPENDS
+    libc.src.wctype.iswalpha
+)

libc/test/src/wctype/iswalpha_test.cpp

@@ -0,0 +1,54 @@
+//===-- Unittests for iswalpha----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/CPP/span.h"
+#include "src/wctype/iswalpha.h"
+
+#include "test/UnitTest/LibcTest.h"
+#include "test/UnitTest/Test.h"
+
+namespace {
+
+// TODO: Merge the wctype tests using this framework.
+constexpr char WALPHA_ARRAY[] = {
+    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
+    'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
+    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
+    'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
+};
+
+bool in_span(int ch, LIBC_NAMESPACE::cpp::span<const char> arr) {
+  for (size_t i = 0; i < arr.size(); ++i)
+    if (static_cast<int>(arr[i]) == ch)
+      return true;
+  return false;
+}
+
+} // namespace
+
+TEST(LlvmLibciswalpha, SimpleTest) {
+  EXPECT_TRUE(LIBC_NAMESPACE::iswalpha('a'));
+  EXPECT_TRUE(LIBC_NAMESPACE::iswalpha('B'));
+
+  EXPECT_FALSE(LIBC_NAMESPACE::iswalpha('3'));
+  EXPECT_FALSE(LIBC_NAMESPACE::iswalpha(' '));
+  EXPECT_FALSE(LIBC_NAMESPACE::iswalpha('?'));
+  EXPECT_FALSE(LIBC_NAMESPACE::iswalpha('\0'));
+  EXPECT_FALSE(LIBC_NAMESPACE::iswalpha(-1));
+}
+
+TEST(LlvmLibciswalpha, DefaultLocale) {
+  // Loops through all characters, verifying that letters return
+  // true and everything else returns false.
+  for (int ch = -255; ch < 255; ++ch) {
+    if (in_span(ch, WALPHA_ARRAY))
+      EXPECT_TRUE(LIBC_NAMESPACE::iswalpha(ch));
+    else
+      EXPECT_FALSE(LIBC_NAMESPACE::iswalpha(ch));
+  }
+}