lshal: test: make mocks more robust

Setup error stream for all tests in ListParseArgsTest.
Otherwise, if lshal writes to error stream, the test
immediately aborts.

Test: lshal_test

Change-Id: I085e764528534e9d2df8e0ccf3181366d20247bc
diff --git a/cmds/lshal/test.cpp b/cmds/lshal/test.cpp
index 501c04d..096b67d 100644
--- a/cmds/lshal/test.cpp
+++ b/cmds/lshal/test.cpp
@@ -226,12 +226,13 @@
     void SetUp() override {
         mockLshal = std::make_unique<NiceMock<MockLshal>>();
         mockList = std::make_unique<MockListCommand>(mockLshal.get());
+        ON_CALL(*mockLshal, err()).WillByDefault(Return(NullableOStream<std::ostream>(err)));
         // ListCommand::parseArgs should parse arguments from the second element
         optind = 1;
     }
     std::unique_ptr<MockLshal> mockLshal;
     std::unique_ptr<MockListCommand> mockList;
-    std::stringstream output;
+    std::stringstream err;
 };
 
 TEST_F(ListParseArgsTest, Args) {
@@ -241,6 +242,7 @@
                                    TableColumnType::SERVER_ADDR, TableColumnType::CLIENT_PIDS}),
                   table.getSelectedColumns());
     });
+    EXPECT_EQ("", err.str());
 }
 
 TEST_F(ListParseArgsTest, Cmds) {
@@ -255,12 +257,12 @@
         EXPECT_THAT(table.getSelectedColumns(), Contains(TableColumnType::CLIENT_CMDS))
                 << "should print client cmds with -m";
     });
+    EXPECT_EQ("", err.str());
 }
 
 TEST_F(ListParseArgsTest, DebugAndNeat) {
-    ON_CALL(*mockLshal, err()).WillByDefault(Return(NullableOStream<std::ostream>(output)));
     EXPECT_NE(0u, mockList->parseArgs(createArg({"lshal", "--neat", "-d"})));
-    EXPECT_THAT(output.str(), StrNe(""));
+    EXPECT_THAT(err.str(), HasSubstr("--neat should not be used with --debug."));
 }
 
 /// Fetch Test