Googletest export

Add ::testing::FieldsAre matcher for objects that support get<> and structured bindings.
PiperOrigin-RevId: 337165285

googlemock/docs/cheat_sheet.md

@@ -403,6 +403,7 @@ messages, you can use:
 | `Field(&class::field, m)`       | `argument.field` (or `argument->field` when `argument` is a plain pointer) matches matcher `m`, where `argument` is an object of type _class_. |
 | `Key(e)`                        | `argument.first` matches `e`, which can be either a value or a matcher. E.g. `Contains(Key(Le(5)))` can verify that a `map` contains a key `<= 5`. |
 | `Pair(m1, m2)`                  | `argument` is an `std::pair` whose `first` field matches `m1` and `second` field matches `m2`. |
+| `FieldsAre(m...)`                   | `argument` is a compatible object where each field matches piecewise with `m...`. A compatible object is any that supports the `std::tuple_size<Obj>`+`get<I>(obj)` protocol. In C++17 and up this also supports types compatible with structured bindings, like aggregates. |
 | `Property(&class::property, m)` | `argument.property()` (or `argument->property()` when `argument` is a plain pointer) matches matcher `m`, where `argument` is an object of type _class_. |
 <!-- mdformat on -->
 

googlemock/include/gmock/gmock-matchers.h

@@ -2879,6 +2879,203 @@ class PairMatcher {
   const SecondMatcher second_matcher_;
 };
 
+template <typename T, size_t... I>
+auto UnpackStructImpl(const T& t, IndexSequence<I...>, int)
+    -> decltype(std::tie(get<I>(t)...)) {
+  static_assert(std::tuple_size<T>::value == sizeof...(I),
+                "Number of arguments doesn't match the number of fields.");
+  return std::tie(get<I>(t)...);
+}
+
+#if defined(__cpp_structured_bindings) && __cpp_structured_bindings >= 201606
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<1>, char) {
+  const auto& [a] = t;
+  return std::tie(a);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<2>, char) {
+  const auto& [a, b] = t;
+  return std::tie(a, b);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<3>, char) {
+  const auto& [a, b, c] = t;
+  return std::tie(a, b, c);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<4>, char) {
+  const auto& [a, b, c, d] = t;
+  return std::tie(a, b, c, d);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<5>, char) {
+  const auto& [a, b, c, d, e] = t;
+  return std::tie(a, b, c, d, e);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<6>, char) {
+  const auto& [a, b, c, d, e, f] = t;
+  return std::tie(a, b, c, d, e, f);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<7>, char) {
+  const auto& [a, b, c, d, e, f, g] = t;
+  return std::tie(a, b, c, d, e, f, g);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<8>, char) {
+  const auto& [a, b, c, d, e, f, g, h] = t;
+  return std::tie(a, b, c, d, e, f, g, h);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<9>, char) {
+  const auto& [a, b, c, d, e, f, g, h, i] = t;
+  return std::tie(a, b, c, d, e, f, g, h, i);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<10>, char) {
+  const auto& [a, b, c, d, e, f, g, h, i, j] = t;
+  return std::tie(a, b, c, d, e, f, g, h, i, j);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<11>, char) {
+  const auto& [a, b, c, d, e, f, g, h, i, j, k] = t;
+  return std::tie(a, b, c, d, e, f, g, h, i, j, k);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<12>, char) {
+  const auto& [a, b, c, d, e, f, g, h, i, j, k, l] = t;
+  return std::tie(a, b, c, d, e, f, g, h, i, j, k, l);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<13>, char) {
+  const auto& [a, b, c, d, e, f, g, h, i, j, k, l, m] = t;
+  return std::tie(a, b, c, d, e, f, g, h, i, j, k, l, m);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<14>, char) {
+  const auto& [a, b, c, d, e, f, g, h, i, j, k, l, m, n] = t;
+  return std::tie(a, b, c, d, e, f, g, h, i, j, k, l, m, n);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<15>, char) {
+  const auto& [a, b, c, d, e, f, g, h, i, j, k, l, m, n, o] = t;
+  return std::tie(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o);
+}
+template <typename T>
+auto UnpackStructImpl(const T& t, MakeIndexSequence<16>, char) {
+  const auto& [a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p] = t;
+  return std::tie(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p);
+}
+#endif  // defined(__cpp_structured_bindings)
+
+template <size_t I, typename T>
+auto UnpackStruct(const T& t)
+    -> decltype((UnpackStructImpl)(t, MakeIndexSequence<I>{}, 0)) {
+  return (UnpackStructImpl)(t, MakeIndexSequence<I>{}, 0);
+}
+
+// Helper function to do comma folding in C++11.
+// The array ensures left-to-right order of evaluation.
+// Usage: VariadicExpand({expr...});
+template <typename T, size_t N>
+void VariadicExpand(const T (&a)[N]) {}
+
+template <typename Struct, typename StructSize>
+class FieldsAreMatcherImpl;
+
+template <typename Struct, size_t... I>
+class FieldsAreMatcherImpl<Struct, IndexSequence<I...>>
+    : public MatcherInterface<Struct> {
+  using UnpackedType =
+      decltype(UnpackStruct<sizeof...(I)>(std::declval<const Struct&>()));
+  using MatchersType = std::tuple<
+      Matcher<const typename std::tuple_element<I, UnpackedType>::type&>...>;
+
+ public:
+  template <typename Inner>
+  explicit FieldsAreMatcherImpl(const Inner& matchers)
+      : matchers_(testing::SafeMatcherCast<
+                  const typename std::tuple_element<I, UnpackedType>::type&>(
+            std::get<I>(matchers))...) {}
+
+  void DescribeTo(::std::ostream* os) const override {
+    const char* separator = "";
+    VariadicExpand(
+        {(*os << separator << "has field #" << I << " that ",
+          std::get<I>(matchers_).DescribeTo(os), separator = ", and ")...});
+  }
+
+  void DescribeNegationTo(::std::ostream* os) const override {
+    const char* separator = "";
+    VariadicExpand({(*os << separator << "has field #" << I << " that ",
+                     std::get<I>(matchers_).DescribeNegationTo(os),
+                     separator = ", or ")...});
+  }
+
+  bool MatchAndExplain(Struct t, MatchResultListener* listener) const override {
+    return MatchInternal((UnpackStruct<sizeof...(I)>)(t), listener);
+  }
+
+ private:
+  bool MatchInternal(UnpackedType tuple, MatchResultListener* listener) const {
+    if (!listener->IsInterested()) {
+      // If the listener is not interested, we don't need to construct the
+      // explanation.
+      bool good = true;
+      VariadicExpand({good = good && std::get<I>(matchers_).Matches(
+                                         std::get<I>(tuple))...});
+      return good;
+    }
+
+    int failed_pos = -1;
+
+    std::vector<StringMatchResultListener> inner_listener(sizeof...(I));
+
+    VariadicExpand(
+        {failed_pos == -1 && !std::get<I>(matchers_).MatchAndExplain(
+                                 std::get<I>(tuple), &inner_listener[I])
+             ? failed_pos = I
+             : 0 ...});
+    if (failed_pos != ~size_t{}) {
+      *listener << "whose field #" << failed_pos << " does not match";
+      PrintIfNotEmpty(inner_listener[failed_pos].str(), listener->stream());
+      return false;
+    }
+
+    *listener << "whose all elements match";
+    const char* separator = ", where";
+    for (size_t index = 0; index < sizeof...(I); ++index) {
+      const std::string str = inner_listener[index].str();
+      if (!str.empty()) {
+        *listener << separator << " field #" << index << " is a value " << str;
+        separator = ", and";
+      }
+    }
+
+    return true;
+  }
+
+  MatchersType matchers_;
+};
+
+template <typename... Inner>
+class FieldsAreMatcher {
+ public:
+  explicit FieldsAreMatcher(Inner... inner) : matchers_(std::move(inner)...) {}
+
+  template <typename Struct>
+  operator Matcher<Struct>() const {  // NOLINT
+    return Matcher<Struct>(
+        new FieldsAreMatcherImpl<const Struct&, IndexSequenceFor<Inner...>>(
+            matchers_));
+  }
+
+ private:
+  std::tuple<Inner...> matchers_;
+};
+
 // Implements ElementsAre() and ElementsAreArray().
 template <typename Container>
 class ElementsAreMatcherImpl : public MatcherInterface<Container> {
@@ -4514,6 +4711,19 @@ Pair(FirstMatcher first_matcher, SecondMatcher second_matcher) {
       first_matcher, second_matcher);
 }
 
+namespace no_adl {
+// FieldsAre(matchers...) matches piecewise the fields of compatible structs.
+// These include those that support `get<I>(obj)`, and when structured bindings
+// are enabled any class that supports them.
+// In particular, `std::tuple`, `std::pair`, `std::array` and aggregate types.
+template <typename... M>
+internal::FieldsAreMatcher<typename std::decay<M>::type...> FieldsAre(
+    M&&... matchers) {
+  return internal::FieldsAreMatcher<typename std::decay<M>::type...>(
+      std::forward<M>(matchers)...);
+}
+}  // namespace no_adl
+
 // Returns a predicate that is satisfied by anything that matches the
 // given matcher.
 template <typename M>
@@ -5053,6 +5263,9 @@ PolymorphicMatcher<internal::ExceptionMatcherImpl<Err>> ThrowsMessage(
 #define GMOCK_INTERNAL_MATCHER_ARG_USAGE(i, data_unused, arg_unused) \
   , gmock_p##i
 
+// To prevent ADL on certain functions we put them on a separate namespace.
+using namespace no_adl;  // NOLINT
+
 }  // namespace testing
 
 GTEST_DISABLE_MSC_WARNINGS_POP_()  //  4251 5046

googlemock/test/gmock-matchers_test.cc

@@ -1643,6 +1643,147 @@ TEST(PairTest, InsideContainsUsingMap) {
   EXPECT_THAT(container, Not(Contains(Pair(3, _))));
 }
 
+TEST(FieldsAreTest, MatchesCorrectly) {
+  std::tuple<int, std::string, double> p(25, "foo", .5);
+
+  // All fields match.
+  EXPECT_THAT(p, FieldsAre(25, "foo", .5));
+  EXPECT_THAT(p, FieldsAre(Ge(20), HasSubstr("o"), DoubleEq(.5)));
+
+  // Some don't match.
+  EXPECT_THAT(p, Not(FieldsAre(26, "foo", .5)));
+  EXPECT_THAT(p, Not(FieldsAre(25, "fo", .5)));
+  EXPECT_THAT(p, Not(FieldsAre(25, "foo", .6)));
+}
+
+TEST(FieldsAreTest, CanDescribeSelf) {
+  Matcher<const pair<std::string, int>&> m1 = FieldsAre("foo", 42);
+  EXPECT_EQ(
+      "has field #0 that is equal to \"foo\""
+      ", and has field #1 that is equal to 42",
+      Describe(m1));
+  EXPECT_EQ(
+      "has field #0 that isn't equal to \"foo\""
+      ", or has field #1 that isn't equal to 42",
+      DescribeNegation(m1));
+}
+
+TEST(FieldsAreTest, CanExplainMatchResultTo) {
+  // The first one that fails is the one that gives the error.
+  Matcher<std::tuple<int, int, int>> m =
+      FieldsAre(GreaterThan(0), GreaterThan(0), GreaterThan(0));
+
+  EXPECT_EQ("whose field #0 does not match, which is 1 less than 0",
+            Explain(m, std::make_tuple(-1, -2, -3)));
+  EXPECT_EQ("whose field #1 does not match, which is 2 less than 0",
+            Explain(m, std::make_tuple(1, -2, -3)));
+  EXPECT_EQ("whose field #2 does not match, which is 3 less than 0",
+            Explain(m, std::make_tuple(1, 2, -3)));
+
+  // If they all match, we get a long explanation of success.
+  EXPECT_EQ(
+      "whose all elements match, "
+      "where field #0 is a value which is 1 more than 0"
+      ", and field #1 is a value which is 2 more than 0"
+      ", and field #2 is a value which is 3 more than 0",
+      Explain(m, std::make_tuple(1, 2, 3)));
+
+  // Only print those that have an explanation.
+  m = FieldsAre(GreaterThan(0), 0, GreaterThan(0));
+  EXPECT_EQ(
+      "whose all elements match, "
+      "where field #0 is a value which is 1 more than 0"
+      ", and field #2 is a value which is 3 more than 0",
+      Explain(m, std::make_tuple(1, 0, 3)));
+
+  // If only one has an explanation, then print that one.
+  m = FieldsAre(0, GreaterThan(0), 0);
+  EXPECT_EQ(
+      "whose all elements match, "
+      "where field #1 is a value which is 1 more than 0",
+      Explain(m, std::make_tuple(0, 1, 0)));
+}
+
+#if defined(__cpp_structured_bindings) && __cpp_structured_bindings >= 201606
+TEST(FieldsAreTest, StructuredBindings) {
+  // testing::FieldsAre can also match aggregates and such with C++17 and up.
+  struct MyType {
+    int i;
+    std::string str;
+  };
+  EXPECT_THAT((MyType{17, "foo"}), FieldsAre(Eq(17), HasSubstr("oo")));
+
+  // Test all the supported arities.
+  struct MyVarType1 {
+    int a;
+  };
+  EXPECT_THAT(MyVarType1{}, FieldsAre(0));
+  struct MyVarType2 {
+    int a, b;
+  };
+  EXPECT_THAT(MyVarType2{}, FieldsAre(0, 0));
+  struct MyVarType3 {
+    int a, b, c;
+  };
+  EXPECT_THAT(MyVarType3{}, FieldsAre(0, 0, 0));
+  struct MyVarType4 {
+    int a, b, c, d;
+  };
+  EXPECT_THAT(MyVarType4{}, FieldsAre(0, 0, 0, 0));
+  struct MyVarType5 {
+    int a, b, c, d, e;
+  };
+  EXPECT_THAT(MyVarType5{}, FieldsAre(0, 0, 0, 0, 0));
+  struct MyVarType6 {
+    int a, b, c, d, e, f;
+  };
+  EXPECT_THAT(MyVarType6{}, FieldsAre(0, 0, 0, 0, 0, 0));
+  struct MyVarType7 {
+    int a, b, c, d, e, f, g;
+  };
+  EXPECT_THAT(MyVarType7{}, FieldsAre(0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType8 {
+    int a, b, c, d, e, f, g, h;
+  };
+  EXPECT_THAT(MyVarType8{}, FieldsAre(0, 0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType9 {
+    int a, b, c, d, e, f, g, h, i;
+  };
+  EXPECT_THAT(MyVarType9{}, FieldsAre(0, 0, 0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType10 {
+    int a, b, c, d, e, f, g, h, i, j;
+  };
+  EXPECT_THAT(MyVarType10{}, FieldsAre(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType11 {
+    int a, b, c, d, e, f, g, h, i, j, k;
+  };
+  EXPECT_THAT(MyVarType11{}, FieldsAre(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType12 {
+    int a, b, c, d, e, f, g, h, i, j, k, l;
+  };
+  EXPECT_THAT(MyVarType12{}, FieldsAre(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType13 {
+    int a, b, c, d, e, f, g, h, i, j, k, l, m;
+  };
+  EXPECT_THAT(MyVarType13{}, FieldsAre(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType14 {
+    int a, b, c, d, e, f, g, h, i, j, k, l, m, n;
+  };
+  EXPECT_THAT(MyVarType14{},
+              FieldsAre(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType15 {
+    int a, b, c, d, e, f, g, h, i, j, k, l, m, n, o;
+  };
+  EXPECT_THAT(MyVarType15{},
+              FieldsAre(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
+  struct MyVarType16 {
+    int a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p;
+  };
+  EXPECT_THAT(MyVarType16{},
+              FieldsAre(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
+}
+#endif
+
 TEST(ContainsTest, WorksWithMoveOnly) {
   ContainerHelper helper;
   EXPECT_CALL(helper, Call(Contains(Pointee(2))));