Multiple prerequisites in partially ordered mock calls in googletest

Question

I was reading partially ordered calls for googletest here and I understoond how their example works. So we can use:

using ::testing::Sequence;
...
  Sequence s1, s2;

  EXPECT_CALL(foo, A())
      .InSequence(s1, s2);
  EXPECT_CALL(bar, B())
      .InSequence(s1);
  EXPECT_CALL(bar, C())
      .InSequence(s2);
  EXPECT_CALL(foo, D())
      .InSequence(s2);

to show the following DAG:

       +---> B
       |
  A ---|
       |
       +---> C ---> D

But I wondered how we can define multiple prerequisites of a call. For example, how I can add DAG constraints for E node in following DAG?

       +---> B ----------+
       |                 |
  A ---|                 |---> E
       |                 |
       +---> C ---> D ---+

Will it be something like this?

using ::testing::Sequence;
...
  Sequence s1, s2, s3;

  EXPECT_CALL(foo, A())
      .InSequence(s1, s2);
  EXPECT_CALL(bar, B())
      .InSequence(s1, s3);
  EXPECT_CALL(bar, C())
      .InSequence(s2);
  EXPECT_CALL(foo, D())
      .InSequence(s2, s3);
  EXPECT_CALL(foo, E())
      .InSequence(s3);

Answer 1

You can use After method to expect some call after certain other call(s). https://google.github.io/googletest/reference/mocking.html#EXPECT_CALL.After

So in your case it will be like this:

Mocked mock;
Sequence s1, s2;
EXPECT_CALL(mock, A).InSequence(s1, s2);
Expectation exp_b = EXPECT_CALL(mock, B).InSequence(s1);
EXPECT_CALL(mock, C).InSequence(s2);
Expectation exp_d = EXPECT_CALL(mock, D).InSequence(s2);
EXPECT_CALL(mock, E).After(exp_b, exp_d);

Full runnable example:

#include <gmock/gmock.h>
#include <gtest/gtest.h>

using ::testing::Sequence;
using ::testing::Expectation;

class Mocked {
public:
    MOCK_METHOD(void, A, ());
    MOCK_METHOD(void, B, ());
    MOCK_METHOD(void, C, ());
    MOCK_METHOD(void, D, ());
    MOCK_METHOD(void, E, ());
};

TEST(Sequences, ABCDE)
{
    Mocked mock;
    Sequence s1, s2;
    EXPECT_CALL(mock, A).InSequence(s1, s2);
    Expectation exp_b = EXPECT_CALL(mock, B).InSequence(s1);
    EXPECT_CALL(mock, C).InSequence(s2);
    Expectation exp_d = EXPECT_CALL(mock, D).InSequence(s2);
    EXPECT_CALL(mock, E).After(exp_b, exp_d);

    mock.A();
    mock.B();
    mock.C();
    mock.D();
    mock.E();
}

P.S. You can completely replace InSequence with After to have a little bit simpler code.