Add the 'googlemock' component of Google Test to LLVM's unittest libraries.

I have two immediate motivations for adding this:
1) It makes writing expectations in tests *dramatically* easier. A
   quick example that is a taste of what is possible:

     std::vector<int> v = ...;
     EXPECT_THAT(v, UnorderedElementsAre(1, 2, 3));

   This checks that v contains '1', '2', and '3' in some order. There
   are a wealth of other helpful matchers like this. They tend to be
   highly generic and STL-friendly so they will in almost all cases work
   out of the box even on custom LLVM data structures.

   I actually find the matcher syntax substantially easier to read even
   for simple assertions:

     EXPECT_THAT(a, Eq(b));
     EXPECT_THAT(b, Ne(c));

   Both of these make it clear what is being *tested* and what is being
   *expected*. With `EXPECT_EQ` this is implicit (the LHS is expected,
   the RHS is tested) and often confusing. With `EXPECT_NE` it is just
   not clear. Even the failure error messages are superior with the
   matcher based expectations.

2) When testing any kind of generic code, you are continually defining
   dummy types with interfaces and then trying to check that the
   interfaces are manipulated in a particular way. This is actually what
   mocks are *good* for -- testing *interface interactions*. With
   generic code, there is often no "fake" or other object that can be
   used.

   For a concrete example of where this is currently causing significant
   pain, look at the pass manager unittests which are riddled with
   counters incremented when methods are called. All of these could be
   replaced with mocks. The result would be more effective at testing
   the code by having tighter constraints. It would be substantially
   more readable and maintainable when updating the code. And the error
   messages on failure would have substantially more information as
   mocks automatically record stack traces and other information *when
   the API is misused* instead of trying to diagnose it after the fact.

I expect that #1 will be the overwhelming majority of the uses of gmock,
but I think that is sufficient to justify having it. I would actually
like to update the coding standards to encourage the use of matchers
rather than any other form of `EXPECT_...` macros as they are IMO
a strict superset in terms of functionality and readability.

I think that #2 is relatively rarely useful, but there *are* cases where
it is useful. Historically, I think misuse of actual mocking as
described in #2 has led to resistance towards this framework. I am
actually sympathetic to this -- mocking can easily be overused. However
I think this is not a significant concern in LLVM. First and foremost,
LLVM has very careful and rare exposure of abstract interfaces or
dependency injection, which are the most prone to abuse with mocks. So
there are few opportunities to abuse them. Second, a large fraction of
LLVM's unittests are testing *generic code* where mocks actually make
tremendous sense. And gmock is well suited to building interfaces that
exercise generic libraries. Finally, I still think we should be willing
to have testing utilities in tree even if they should be used rarely. We
can use code review to help guide the usage here.

For a longer and more complete discussion of this, see the llvm-dev
thread here:
http://lists.llvm.org/pipermail/llvm-dev/2017-January/108672.html

The general consensus seems that this is a reasonable direction to start
down, but that doesn't mean we should race ahead and use this
everywhere. I have one test that is blocked on this to land and that was
specifically used as an example. Before widespread adoption, I'm going
to work up some (brief) guidelines as some of these facilities should be
used sparingly and carefully.

Differential Revision: https://reviews.llvm.org/D28156

llvm-svn: 291606

1 files changed, 279 insertions, 0 deletions

diff --git a/llvm/utils/unittest/googlemock/include/gmock/internal/gmock-generated-internal-utils.h b/llvm/utils/unittest/googlemock/include/gmock/internal/gmock-generated-internal-utils.h
new file mode 100644
index 00000000000..7811e43f87c
--- /dev/null
+++ b/llvm/utils/unittest/googlemock/include/gmock/internal/gmock-generated-internal-utils.h
@@ -0,0 +1,279 @@
+// This file was GENERATED by command:
+//     pump.py gmock-generated-internal-utils.h.pump
+// DO NOT EDIT BY HAND!!!
+
+// Copyright 2007, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: wan@google.com (Zhanyong Wan)
+
+// Google Mock - a framework for writing C++ mock classes.
+//
+// This file contains template meta-programming utility classes needed
+// for implementing Google Mock.
+
+#ifndef GMOCK_INCLUDE_GMOCK_INTERNAL_GMOCK_GENERATED_INTERNAL_UTILS_H_
+#define GMOCK_INCLUDE_GMOCK_INTERNAL_GMOCK_GENERATED_INTERNAL_UTILS_H_
+
+#include "gmock/internal/gmock-port.h"
+
+namespace testing {
+
+template <typename T>
+class Matcher;
+
+namespace internal {
+
+// An IgnoredValue object can be implicitly constructed from ANY value.
+// This is used in implementing the IgnoreResult(a) action.
+class IgnoredValue {
+ public:
+  // This constructor template allows any value to be implicitly
+  // converted to IgnoredValue.  The object has no data member and
+  // doesn't try to remember anything about the argument.  We
+  // deliberately omit the 'explicit' keyword in order to allow the
+  // conversion to be implicit.
+  template <typename T>
+  IgnoredValue(const T& /* ignored */) {}  // NOLINT(runtime/explicit)
+};
+
+// MatcherTuple<T>::type is a tuple type where each field is a Matcher
+// for the corresponding field in tuple type T.
+template <typename Tuple>
+struct MatcherTuple;
+
+template <>
+struct MatcherTuple< ::testing::tuple<> > {
+  typedef ::testing::tuple< > type;
+};
+
+template <typename A1>
+struct MatcherTuple< ::testing::tuple<A1> > {
+  typedef ::testing::tuple<Matcher<A1> > type;
+};
+
+template <typename A1, typename A2>
+struct MatcherTuple< ::testing::tuple<A1, A2> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2> > type;
+};
+
+template <typename A1, typename A2, typename A3>
+struct MatcherTuple< ::testing::tuple<A1, A2, A3> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2>, Matcher<A3> > type;
+};
+
+template <typename A1, typename A2, typename A3, typename A4>
+struct MatcherTuple< ::testing::tuple<A1, A2, A3, A4> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2>, Matcher<A3>,
+      Matcher<A4> > type;
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5>
+struct MatcherTuple< ::testing::tuple<A1, A2, A3, A4, A5> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2>, Matcher<A3>, Matcher<A4>,
+      Matcher<A5> > type;
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5,
+    typename A6>
+struct MatcherTuple< ::testing::tuple<A1, A2, A3, A4, A5, A6> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2>, Matcher<A3>, Matcher<A4>,
+      Matcher<A5>, Matcher<A6> > type;
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5,
+    typename A6, typename A7>
+struct MatcherTuple< ::testing::tuple<A1, A2, A3, A4, A5, A6, A7> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2>, Matcher<A3>, Matcher<A4>,
+      Matcher<A5>, Matcher<A6>, Matcher<A7> > type;
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5,
+    typename A6, typename A7, typename A8>
+struct MatcherTuple< ::testing::tuple<A1, A2, A3, A4, A5, A6, A7, A8> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2>, Matcher<A3>, Matcher<A4>,
+      Matcher<A5>, Matcher<A6>, Matcher<A7>, Matcher<A8> > type;
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5,
+    typename A6, typename A7, typename A8, typename A9>
+struct MatcherTuple< ::testing::tuple<A1, A2, A3, A4, A5, A6, A7, A8, A9> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2>, Matcher<A3>, Matcher<A4>,
+      Matcher<A5>, Matcher<A6>, Matcher<A7>, Matcher<A8>, Matcher<A9> > type;
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5,
+    typename A6, typename A7, typename A8, typename A9, typename A10>
+struct MatcherTuple< ::testing::tuple<A1, A2, A3, A4, A5, A6, A7, A8, A9,
+    A10> > {
+  typedef ::testing::tuple<Matcher<A1>, Matcher<A2>, Matcher<A3>, Matcher<A4>,
+      Matcher<A5>, Matcher<A6>, Matcher<A7>, Matcher<A8>, Matcher<A9>,
+      Matcher<A10> > type;
+};
+
+// Template struct Function<F>, where F must be a function type, contains
+// the following typedefs:
+//
+//   Result:               the function's return type.
+//   ArgumentN:            the type of the N-th argument, where N starts with 1.
+//   ArgumentTuple:        the tuple type consisting of all parameters of F.
+//   ArgumentMatcherTuple: the tuple type consisting of Matchers for all
+//                         parameters of F.
+//   MakeResultVoid:       the function type obtained by substituting void
+//                         for the return type of F.
+//   MakeResultIgnoredValue:
+//                         the function type obtained by substituting Something
+//                         for the return type of F.
+template <typename F>
+struct Function;
+
+template <typename R>
+struct Function<R()> {
+  typedef R Result;
+  typedef ::testing::tuple<> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid();
+  typedef IgnoredValue MakeResultIgnoredValue();
+};
+
+template <typename R, typename A1>
+struct Function<R(A1)>
+    : Function<R()> {
+  typedef A1 Argument1;
+  typedef ::testing::tuple<A1> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1);
+  typedef IgnoredValue MakeResultIgnoredValue(A1);
+};
+
+template <typename R, typename A1, typename A2>
+struct Function<R(A1, A2)>
+    : Function<R(A1)> {
+  typedef A2 Argument2;
+  typedef ::testing::tuple<A1, A2> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2);
+};
+
+template <typename R, typename A1, typename A2, typename A3>
+struct Function<R(A1, A2, A3)>
+    : Function<R(A1, A2)> {
+  typedef A3 Argument3;
+  typedef ::testing::tuple<A1, A2, A3> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2, A3);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2, A3);
+};
+
+template <typename R, typename A1, typename A2, typename A3, typename A4>
+struct Function<R(A1, A2, A3, A4)>
+    : Function<R(A1, A2, A3)> {
+  typedef A4 Argument4;
+  typedef ::testing::tuple<A1, A2, A3, A4> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2, A3, A4);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2, A3, A4);
+};
+
+template <typename R, typename A1, typename A2, typename A3, typename A4,
+    typename A5>
+struct Function<R(A1, A2, A3, A4, A5)>
+    : Function<R(A1, A2, A3, A4)> {
+  typedef A5 Argument5;
+  typedef ::testing::tuple<A1, A2, A3, A4, A5> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2, A3, A4, A5);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2, A3, A4, A5);
+};
+
+template <typename R, typename A1, typename A2, typename A3, typename A4,
+    typename A5, typename A6>
+struct Function<R(A1, A2, A3, A4, A5, A6)>
+    : Function<R(A1, A2, A3, A4, A5)> {
+  typedef A6 Argument6;
+  typedef ::testing::tuple<A1, A2, A3, A4, A5, A6> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2, A3, A4, A5, A6);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2, A3, A4, A5, A6);
+};
+
+template <typename R, typename A1, typename A2, typename A3, typename A4,
+    typename A5, typename A6, typename A7>
+struct Function<R(A1, A2, A3, A4, A5, A6, A7)>
+    : Function<R(A1, A2, A3, A4, A5, A6)> {
+  typedef A7 Argument7;
+  typedef ::testing::tuple<A1, A2, A3, A4, A5, A6, A7> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2, A3, A4, A5, A6, A7);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2, A3, A4, A5, A6, A7);
+};
+
+template <typename R, typename A1, typename A2, typename A3, typename A4,
+    typename A5, typename A6, typename A7, typename A8>
+struct Function<R(A1, A2, A3, A4, A5, A6, A7, A8)>
+    : Function<R(A1, A2, A3, A4, A5, A6, A7)> {
+  typedef A8 Argument8;
+  typedef ::testing::tuple<A1, A2, A3, A4, A5, A6, A7, A8> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2, A3, A4, A5, A6, A7, A8);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2, A3, A4, A5, A6, A7, A8);
+};
+
+template <typename R, typename A1, typename A2, typename A3, typename A4,
+    typename A5, typename A6, typename A7, typename A8, typename A9>
+struct Function<R(A1, A2, A3, A4, A5, A6, A7, A8, A9)>
+    : Function<R(A1, A2, A3, A4, A5, A6, A7, A8)> {
+  typedef A9 Argument9;
+  typedef ::testing::tuple<A1, A2, A3, A4, A5, A6, A7, A8, A9> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2, A3, A4, A5, A6, A7, A8, A9);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2, A3, A4, A5, A6, A7, A8,
+      A9);
+};
+
+template <typename R, typename A1, typename A2, typename A3, typename A4,
+    typename A5, typename A6, typename A7, typename A8, typename A9,
+    typename A10>
+struct Function<R(A1, A2, A3, A4, A5, A6, A7, A8, A9, A10)>
+    : Function<R(A1, A2, A3, A4, A5, A6, A7, A8, A9)> {
+  typedef A10 Argument10;
+  typedef ::testing::tuple<A1, A2, A3, A4, A5, A6, A7, A8, A9,
+      A10> ArgumentTuple;
+  typedef typename MatcherTuple<ArgumentTuple>::type ArgumentMatcherTuple;
+  typedef void MakeResultVoid(A1, A2, A3, A4, A5, A6, A7, A8, A9, A10);
+  typedef IgnoredValue MakeResultIgnoredValue(A1, A2, A3, A4, A5, A6, A7, A8,
+      A9, A10);
+};
+
+}  // namespace internal
+
+}  // namespace testing
+
+#endif  // GMOCK_INCLUDE_GMOCK_INTERNAL_GMOCK_GENERATED_INTERNAL_UTILS_H_