[unittest, ADT] Add unit tests for itostr & utostr

[thopre]

llvm/unittests/ADT/StringExtrasTest.cpp

198

Since there's no comment, I'm not sure whether it is supported by the API or not. I'd be tempted to add an assert and a comment not to support it.

[jhenderson]

llvm/unittests/ADT/StringExtrasTest.cpp

195–196

Here, and in the below cases using the max/min values, I wonder whether it would be more robust to write something like:

EXPECT_EQ(std::to_string(MaxUint64), utostr(MaxUint64));
EXPECT_EQ("-" + std::to_string(MaxUint64), utostr(MaxUint64, /*isNeg=*/true);

etc.

I'd expect them to produce identical output, but it also is easier to confirm the expected number. It also removes any concerns about numeric representation (2's complement etc).

198

I'm inclined to leave it as-is. It's possible it was a simple oversight by the original developer, but I think it's okay to permit it for consistency. People could be using it in the sense of "subtract 0" rather than "negative 0" in theory, apart from anything else.

[thopre]

llvm/unittests/ADT/StringExtrasTest.cpp

195–196

It's what I did originally but I was not sure if it was fine to rely on std::to_string being correct.

[thopre]

Use std::to_string to test API for big values

[jhenderson]

LGTM.

llvm/unittests/ADT/StringExtrasTest.cpp

195–196

I think if we can't rely on standard library functions doing the right thing, we're in trouble...

llvm/unittests/ADT/StringExtrasTest.cpp

TEST(StringExtras, ConvertToCamelFromSnakeCase) {
   testConvertToCamelCase(true, "A", "A");
   testConvertToCamelCase(true, "_", "_");
   testConvertToCamelCase(true, "a", "A");
   testConvertToCamelCase(true, "OpName", "OpName");
   testConvertToCamelCase(true, "_OpName", "_OpName");
   testConvertToCamelCase(true, "Op_Name", "Op_Name");
   testConvertToCamelCase(true, "opName", "OpName");
 }
+
+constexpr uint64_t MaxUint64 = std::numeric_limits<uint64_t>::max();
+constexpr int64_t MaxInt64 = std::numeric_limits<int64_t>::max();
+constexpr int64_t MinInt64 = std::numeric_limits<int64_t>::min();
+
+TEST(StringExtras, UToStr) {
+  EXPECT_EQ("0", utostr(0));
+  EXPECT_EQ("0", utostr(0, /*isNeg=*/false));
+  EXPECT_EQ("1", utostr(1));
+  EXPECT_EQ("1", utostr(1, /*isNeg=*/false));
+  EXPECT_EQ(std::to_string(MaxUint64), utostr(MaxUint64));
+  EXPECT_EQ(std::to_string(MaxUint64), utostr(MaxUint64, /*isNeg=*/false));
+
+  EXPECT_EQ("-0", utostr(0, /*isNeg=*/true));
+  EXPECT_EQ("-1", utostr(1, /*isNeg=*/true));
+  EXPECT_EQ("-" + std::to_string(MaxInt64), utostr(MaxInt64, /*isNeg=*/true));
+  constexpr uint64_t MinusMinInt64 = -static_cast<uint64_t>(MinInt64);
+  EXPECT_EQ("-" + std::to_string(MinusMinInt64),
+            utostr(MinusMinInt64, /*isNeg=*/true));
+  EXPECT_EQ("-" + std::to_string(MaxUint64), utostr(MaxUint64, /*isNeg=*/true));
+}
+
+TEST(StringExtras, IToStr) {
+  EXPECT_EQ("0", itostr(0));
+  EXPECT_EQ("1", itostr(1));
+  EXPECT_EQ("-1", itostr(-1));
+  EXPECT_EQ(std::to_string(MinInt64), itostr(MinInt64));
+  EXPECT_EQ(std::to_string(MaxInt64), itostr(MaxInt64));
+}