--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mlir/unittests/TableGen/FormatTest.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,158 @@
+//===- FormatTest.cpp - TableGen Format Utility Tests ---------------------===//
+//
+// 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 "mlir/TableGen/Format.h"
+#include "gmock/gmock.h"
+
+using mlir::tblgen::FmtContext;
+using mlir::tblgen::tgfmt;
+using ::testing::StrEq;
+
+TEST(FormatTest, EmptyFmtStr) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("", &ctx));
+  EXPECT_TRUE(result.empty());
+}
+
+// Allow extra unused positional parameters
+TEST(FormatTest, EmptyFmtStrExtraParams) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("", &ctx, "a", "b", "c"));
+  EXPECT_TRUE(result.empty());
+}
+
+// Allow unused placeholder substitution in context
+TEST(FormatTest, EmptyFmtStrPopulatedCtx) {
+  FmtContext ctx;
+  ctx.withBuilder("builder");
+  std::string result = std::string(tgfmt("", &ctx));
+  EXPECT_TRUE(result.empty());
+}
+
+TEST(FormatTest, LiteralFmtStr) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("void foo {}", &ctx));
+  EXPECT_THAT(result, StrEq("void foo {}"));
+}
+
+// Print single dollar literally
+TEST(FormatTest, AdjacentDollar) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("$", &ctx));
+  EXPECT_THAT(result, StrEq("$"));
+}
+
+// Print dangling dollar literally
+TEST(FormatTest, DanglingDollar) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("foo bar baz$", &ctx));
+  EXPECT_THAT(result, StrEq("foo bar baz$"));
+}
+
+// Allow escape dollars with '$$'
+TEST(FormatTest, EscapeDollars) {
+  FmtContext ctx;
+  std::string result =
+      std::string(tgfmt("$$ $$$$ $$$0 $$$_self", &ctx.withSelf("self"), "-0"));
+  EXPECT_THAT(result, StrEq("$ $$ $-0 $self"));
+}
+
+TEST(FormatTest, PositionalFmtStr) {
+  FmtContext ctx;
+  std::string b = "b";
+  int c = 42;
+  char d = 'd';
+  std::string result =
+      std::string(tgfmt("$0 $1 $2 $3", &ctx, "a", b, c + 1, d));
+  EXPECT_THAT(result, StrEq("a b 43 d"));
+}
+
+// Output the placeholder if missing substitution
+TEST(FormatTest, PositionalFmtStrMissingParams) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("$0 %1 $2", &ctx));
+  EXPECT_THAT(result, StrEq("$0<no-subst-found> %1 $2<no-subst-found>"));
+}
+
+// Allow flexible reference of positional parameters
+TEST(FormatTest, PositionalFmtStrFlexibleRef) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("$2 $0 $2", &ctx, "a", "b", "c"));
+  EXPECT_THAT(result, StrEq("c a c"));
+}
+
+TEST(FormatTest, PositionalFmtStrNoWhitespace) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("foo$0bar", &ctx, "-"));
+  EXPECT_THAT(result, StrEq("foo-bar"));
+}
+
+TEST(FormatTest, PlaceHolderFmtStrWithSelf) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("$_self", &ctx.withSelf("sss")));
+  EXPECT_THAT(result, StrEq("sss"));
+}
+
+TEST(FormatTest, PlaceHolderFmtStrWithBuilder) {
+  FmtContext ctx;
+
+  std::string result = std::string(tgfmt("$_builder", &ctx.withBuilder("bbb")));
+  EXPECT_THAT(result, StrEq("bbb"));
+}
+
+TEST(FormatTest, PlaceHolderFmtStrWithOp) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("$_op", &ctx.withOp("ooo")));
+  EXPECT_THAT(result, StrEq("ooo"));
+}
+
+TEST(FormatTest, PlaceHolderMissingCtx) {
+  std::string result = std::string(tgfmt("$_op", nullptr));
+  EXPECT_THAT(result, StrEq("$_op<no-subst-found>"));
+}
+
+TEST(FormatTest, PlaceHolderMissingSubst) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("$_op", &ctx.withBuilder("builder")));
+  EXPECT_THAT(result, StrEq("$_op<no-subst-found>"));
+}
+
+// Test commonly used delimiters in C++
+TEST(FormatTest, PlaceHolderFmtStrDelimiter) {
+  FmtContext ctx;
+  ctx.addSubst("m", "");
+  std::string result = std::string(tgfmt("$m{$m($m[$m]$m)$m}$m|", &ctx));
+  EXPECT_THAT(result, StrEq("{([])}|"));
+}
+
+// Test allowed characters in placeholder symbol
+TEST(FormatTest, CustomPlaceHolderFmtStrPlaceHolderChars) {
+  FmtContext ctx;
+  ctx.addSubst("m", "0 ");
+  ctx.addSubst("m1", "1 ");
+  ctx.addSubst("m2C", "2 ");
+  ctx.addSubst("M_3", "3 ");
+  std::string result = std::string(tgfmt("$m$m1$m2C$M_3", &ctx));
+  EXPECT_THAT(result, StrEq("0 1 2 3 "));
+}
+
+TEST(FormatTest, CustomPlaceHolderFmtStrUnregisteredPlaceHolders) {
+  FmtContext ctx;
+  std::string result = std::string(tgfmt("foo($awesome, $param)", &ctx));
+  EXPECT_THAT(result,
+              StrEq("foo($awesome<no-subst-found>, $param<no-subst-found>)"));
+}
+
+TEST(FormatTest, MixedFmtStr) {
+  FmtContext ctx;
+  ctx.withBuilder("bbb");
+
+  std::string result = std::string(tgfmt("$_builder.build($_self, {$0, $1})",
+                                         &ctx.withSelf("sss"), "a", "b"));
+  EXPECT_THAT(result, StrEq("bbb.build(sss, {a, b})"));
+}