[TEST] Test failure in ZipkinExporterTestPeer.ExportJsonIntegrationTest

[marcalff]

............................................Subprocess aborted***Exception:   0.30 sec
Running main() from /home/runner/.conan2/p/b/gtestf183f6b0ea446/b/src/googletest/src/gtest_main.cc
Note: Google Test filter = ZipkinExporterTestPeer.ExportJsonIntegrationTest
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from ZipkinExporterTestPeer
[ RUN      ] ZipkinExporterTestPeer.ExportJsonIntegrationTest
/home/runner/work/opentelemetry-cpp/opentelemetry-cpp/exporters/zipkin/test/zipkin_exporter_test.cc:159: Failure
Mock function called more times than expected - returning default value.
    Function call: Post(@0x7f85931fea40 http://localhost:9411/api/v2/spans, @0x5638e8efa3e0 328-byte object <00-00 00-00 00-00 00-00 F8-A3 EF-E8 38-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 18-A4 EF-E8 38-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 ... F8-A4 EF-E8 38-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 18-A5 EF-E8 38-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00>, @0x7f85931fea20 { '[' (91, 0x5B), '{' (123, 0x7B), '"' (34, 0x22), 'd' (100, 0x64), 'u' (117, 0x75), 'r' (114, 0x72), 'a' (97, 0x61), 't' (116, 0x74), 'i' (105, 0x69), 'o' (111, 0x6F), 'n' (110, 0x6E), '"' (34, 0x22), ':' (58, 0x3A), '1' (49, 0x31), '2' (50, 0x32), '2' (50, 0x32), ',' (44, 0x2C), '"' (34, 0x22), 'i' (105, 0x69), 'd' (100, 0x64), '"' (34, 0x22), ':' (58, 0x3A), '"' (34, 0x22), '5' (53, 0x35), '4' (52, 0x34), '8' (56, 0x38), 'b' (98, 0x62), 'e' (101, 0x65), 'e' (101, 0x65), 'f' (102, 0x66), '1' (49, 0x31), '1' (49, 0x31), ... }, @0x563914ce52b8 { ("content-type", "application/json") }, @0x7f85931fe9d4 4-byte object <00-00 00-00>)
         Expected: to be called once
           Actual: called twice - over-saturated and active

terminate called after throwing an instance of 'std::runtime_error'
  what():  Mock function called more times than expected - returning default value.
    Function call: Post(@0x7f85931fea40 http://localhost:9411/api/v2/spans, @0x5638e8efa3e0 328-byte object <00-00 00-00 00-00 00-00 F8-A3 EF-E8 38-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 18-A4 EF-E8 38-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 ... F8-A4 EF-E8 38-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 18-A5 EF-E8 38-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00>, @0x7f85931fea20 { '[' (91, 0x5B), '{' (123, 0x7B), '"' (34, 0x22), 'd' (100, 0x64), 'u' (117, 0x75), 'r' (114, 0x72), 'a' (97, 0x61), 't' (116, 0x74), 'i' (105, 0x69), 'o' (111, 0x6F), 'n' (110, 0x6E), '"' (34, 0x22), ':' (58, 0x3A), '1' (49, 0x31), '2' (50, 0x32), '2' (50, 0x32), ',' (44, 0x2C), '"' (34, 0x22), 'i' (105, 0x69), 'd' (100, 0x64), '"' (34, 0x22), ':' (58, 0x3A), '"' (34, 0x22), '5' (53, 0x35), '4' (52, 0x34), '8' (56, 0x38), 'b' (98, 0x62), 'e' (101, 0x65), 'e' (101, 0x65), 'f' (102, 0x66), '1' (49, 0x31), '1' (49, 0x31), ... }, @0x563914ce52b8 { ("content-type", "application/json") }, @0x7f85931fe9d4 4-byte object <00-00 00-00>)
    The mock function has no default action set, and its return type has no default value set.

Root cause likely similar to #3721 , with the batch span processor making 2 exports instead of 1.