All of these are specific to tests, not the library code.
For the moment, protocol_xfer still leaks connections (and anything they hold on to) because it is very difficult to disentangle them from the connection manager in the partially implemented state they are in.
This fixes leaks of options in the account option test (these two leaks occur for every test since they all leak the option):
61 (48 direct, 13 indirect) bytes in 1 blocks are definitely lost in loss record 133 of 276
   at 0x4848464: calloc (vg_replace_malloc.c:1340)
   by 0x49F75F0: g_malloc0 (gmem.c:163)
   by 0x48C3B2E: purple_account_option_new (purpleaccountoption.c:78)
   by 0x4014AF: test_purple_account_option_copy_int (test_account_option.c:67)
   by 0x4A1CC7D: UnknownInlinedFun (gtestutils.c:2933)
   by 0x4A1CC7D: g_test_run_suite_internal (gtestutils.c:3021)
   by 0x4A1C9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A1C9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A1D181: g_test_run_suite (gtestutils.c:3115)
   by 0x4A156EC: UnknownInlinedFun (gtestutils.c:2234)
   by 0x4A156EC: g_test_run (gtestutils.c:2221)
   by 0x401721: main (test_account_option.c:157)

61 (48 direct, 13 indirect) bytes in 1 blocks are definitely lost in loss record 134 of 276
   at 0x4848464: calloc (vg_replace_malloc.c:1340)
   by 0x49F75F0: g_malloc0 (gmem.c:163)
   by 0x48C3BC7: purple_account_option_copy (purpleaccountoption.c:93)
   by 0x4014BF: test_purple_account_option_copy_int (test_account_option.c:68)
   by 0x4A1CC7D: UnknownInlinedFun (gtestutils.c:2933)
   by 0x4A1CC7D: g_test_run_suite_internal (gtestutils.c:3021)
   by 0x4A1C9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A1C9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A1D181: g_test_run_suite (gtestutils.c:3115)
   by 0x4A156EC: UnknownInlinedFun (gtestutils.c:2234)
   by 0x4A156EC: g_test_run (gtestutils.c:2221)
   by 0x401721: main (test_account_option.c:157)

leaks in the credential manager test (times 3 for read/write/cancel tests):
69 (16 direct, 53 indirect) bytes in 1 blocks are definitely lost in loss record 2,427 of 3,503
   at 0x484386F: malloc (vg_replace_malloc.c:393)
   by 0x4A58168: g_malloc (gmem.c:130)
   by 0x4A6FAB5: g_slice_alloc (gslice.c:1074)
   by 0x4A700EC: g_slice_alloc0 (gslice.c:1100)
   by 0x4A3BECB: g_error_allocate (gerror.c:710)
   by 0x4A3C93F: UnknownInlinedFun (gerror.c:724)
   by 0x4A3C93F: g_error_new_valist (gerror.c:766)
   by 0x4BEE558: g_task_return_new_error (gtask.c:1941)
   by 0x48D82C0: purple_credential_manager_read_password_async (purplecredentialmanager.c:492)
   by 0x403634: test_purple_credential_manager_no_provider_read_password_idle (test_credential_manager.c:329)
   by 0x4A4ECB1: g_idle_dispatch (gmain.c:6124)
   by 0x4A4FCBE: UnknownInlinedFun (gmain.c:3444)
   by 0x4A4FCBE: g_main_context_dispatch (gmain.c:4162)
   by 0x4AA5597: g_main_context_iterate.constprop.0 (gmain.c:4238)
   by 0x4A4F28E: g_main_loop_run (gmain.c:4438)
   by 0x40369F: test_purple_credential_manager_no_provider_read_password_async (test_credential_manager.c:345)
   by 0x4A7DC7D: UnknownInlinedFun (gtestutils.c:2933)
   by 0x4A7DC7D: g_test_run_suite_internal (gtestutils.c:3021)
   by 0x4A7D9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A7D9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A7E181: g_test_run_suite (gtestutils.c:3115)
   by 0x4A766EC: UnknownInlinedFun (gtestutils.c:2234)
   by 0x4A766EC: g_test_run (gtestutils.c:2221)
   by 0x4048F6: main (test_credential_manager.c:695)

a leak in the image test:
161 bytes in 1 blocks are definitely lost in loss record 260 of 274
   at 0x484386F: malloc (vg_replace_malloc.c:393)
   by 0x4A55363: g_try_malloc (gmem.c:286)
   by 0x4A3D630: UnknownInlinedFun (gfileutils.c:819)
   by 0x4A3D630: UnknownInlinedFun (gfileutils.c:924)
   by 0x4A3D630: g_file_get_contents (gfileutils.c:1027)
   by 0x401890: test_image_new_from_file (test_image.c:144)
   by 0x4A7DC7D: UnknownInlinedFun (gtestutils.c:2933)
   by 0x4A7DC7D: g_test_run_suite_internal (gtestutils.c:3021)
   by 0x4A7D9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A7E181: g_test_run_suite (gtestutils.c:3115)
   by 0x4A766EC: UnknownInlinedFun (gtestutils.c:2234)
   by 0x4A766EC: g_test_run (gtestutils.c:2221)
   by 0x40195D: main (test_image.c:172)

a leak in queued output stream test:
72 (40 direct, 32 indirect) bytes in 1 blocks are definitely lost in loss record 219 of 396
   at 0x49D51EF: g_type_create_instance (gtype.c:1909)
   by 0x49BAC1F: g_object_new_internal (gobject.c:2228)
   by 0x49BC247: g_object_new_with_properties (gobject.c:2391)
   by 0x49BCFF0: g_object_new (gobject.c:2037)
   by 0x402003: test_queued_output_stream_push_bytes_async_error (test_queued_output_stream.c:219)
   by 0x4A7DC7D: UnknownInlinedFun (gtestutils.c:2933)
   by 0x4A7DC7D: g_test_run_suite_internal (gtestutils.c:3021)
   by 0x4A7D9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A7E181: g_test_run_suite (gtestutils.c:3115)
   by 0x4A766EC: UnknownInlinedFun (gtestutils.c:2234)
   by 0x4A766EC: g_test_run (gtestutils.c:2221)
   by 0x402429: main (test_queued_output_stream.c:280)

and protocol xfer tests (times 3 for each test that creates a test protocol object):
112 (48 direct, 64 indirect) bytes in 1 blocks are definitely lost in loss record 3,430 of 3,698
   at 0x49D51EF: g_type_create_instance (gtype.c:1909)
   by 0x49BAC1F: g_object_new_internal (gobject.c:2228)
   by 0x49BC247: g_object_new_with_properties (gobject.c:2391)
   by 0x49BCFF0: g_object_new (gobject.c:2037)
   by 0x40291C: test_purple_protocol_xfer_send_file_func (test_protocol_xfer.c:146)
   by 0x4A7DC7D: UnknownInlinedFun (gtestutils.c:2933)
   by 0x4A7DC7D: g_test_run_suite_internal (gtestutils.c:3021)
   by 0x4A7D9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A7E181: g_test_run_suite (gtestutils.c:3115)
   by 0x4A766EC: UnknownInlinedFun (gtestutils.c:2234)
   by 0x4A766EC: g_test_run (gtestutils.c:2221)
   by 0x402B64: main (test_protocol_xfer.c:195)

and util tests (times 3 for each call to purple_text_strip_mnemonic in the test):
5 bytes in 1 blocks are definitely lost in loss record 5 of 247
   at 0x484386F: malloc (vg_replace_malloc.c:393)
   by 0x49F7168: g_malloc (gmem.c:130)
   by 0x491975B: purple_text_strip_mnemonic (util.c:895)
   by 0x4015B0: test_util_text_strip_mnemonic (test_util.c:49)
   by 0x4A1CC7D: UnknownInlinedFun (gtestutils.c:2933)
   by 0x4A1CC7D: g_test_run_suite_internal (gtestutils.c:3021)
   by 0x4A1C9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A1C9E4: g_test_run_suite_internal (gtestutils.c:3038)
   by 0x4A1D181: g_test_run_suite (gtestutils.c:3115)
   by 0x4A156EC: UnknownInlinedFun (gtestutils.c:2234)
   by 0x4A156EC: g_test_run (gtestutils.c:2221)
   by 0x401901: main (test_util.c:224)

and these leaks in any test that initializes the test UI:
4,104 bytes in 1 blocks are possibly lost in loss record 3,451 of 3,457
   at 0x484386F: malloc (vg_replace_malloc.c:393)
   by 0x5235B67: sqlite3MemMalloc.lto_priv.0 (sqlite3.c:25493)
   by 0x5232797: UnknownInlinedFun (sqlite3.c:29181)
   by 0x5232797: UnknownInlinedFun (sqlite3.c:29227)
   by 0x5232797: sqlite3Malloc.lto_priv.0 (sqlite3.c:29221)
   by 0x523BD8B: pcache1Alloc.lto_priv.0 (sqlite3.c:53546)
   by 0x5249A8B: UnknownInlinedFun (sqlite3.c:53675)
   by 0x5249A8B: allocateTempSpace (sqlite3.c:70848)
   by 0x52625A6: sqlite3VdbeExec.lto_priv.0 (sqlite3.c:93857)
   by 0x525CBEE: UnknownInlinedFun (sqlite3.c:87995)
   by 0x525CBEE: UnknownInlinedFun (sqlite3.c:88056)
   by 0x525CBEE: sqlite3_step (sqlite3.c:88045)
   by 0x529B324: sqlite3_exec (sqlite3.c:131002)
   by 0x48FD558: purple_sqlite3_run_migration (purplesqlite3.c:37)
   by 0x48FDBB4: purple_sqlite3_run_migrations_from_resources (purplesqlite3.c:195)
   by 0x48FDED9: purple_sqlite_history_adapter_run_migrations (purplesqlitehistoryadapter.c:69)
   by 0x48FE7F0: purple_sqlite_history_adapter_activate (purplesqlitehistoryadapter.c:287)
   by 0x48DB656: purple_history_adapter_activate (purplehistoryadapter.c:181)
   by 0x48DC9BC: purple_history_manager_set_active (purplehistorymanager.c:308)
   by 0x402BA8: test_ui_init_history (test_ui.c:132)
   by 0x402C80: test_ui_purple_init (test_ui.c:167)
   by 0x4027BB: main (test_contact.c:88)

4,368 bytes in 1 blocks are possibly lost in loss record 3,453 of 3,457
   at 0x484386F: malloc (vg_replace_malloc.c:393)
   by 0x5235B67: sqlite3MemMalloc.lto_priv.0 (sqlite3.c:25493)
   by 0x5232797: UnknownInlinedFun (sqlite3.c:29181)
   by 0x5232797: UnknownInlinedFun (sqlite3.c:29227)
   by 0x5232797: sqlite3Malloc.lto_priv.0 (sqlite3.c:29221)
   by 0x523BD8B: pcache1Alloc.lto_priv.0 (sqlite3.c:53546)
   by 0x5240077: UnknownInlinedFun (sqlite3.c:53634)
   by 0x5240077: pcache1FetchStage2 (sqlite3.c:54104)
   by 0x5243E9C: UnknownInlinedFun (sqlite3.c:52671)
   by 0x5243E9C: getPageNormal.lto_priv.0 (sqlite3.c:60628)
   by 0x524A510: UnknownInlinedFun (sqlite3.c:60805)
   by 0x524A510: btreeGetPage.lto_priv.0 (sqlite3.c:70289)
   by 0x524C2F6: UnknownInlinedFun (sqlite3.c:71257)
   by 0x524C2F6: sqlite3BtreeBeginTrans.lto_priv.0 (sqlite3.c:71647)
   by 0x5266B3A: sqlite3VdbeExec.lto_priv.0 (sqlite3.c:93532)
   by 0x525CBEE: UnknownInlinedFun (sqlite3.c:87995)
   by 0x525CBEE: UnknownInlinedFun (sqlite3.c:88056)
   by 0x525CBEE: sqlite3_step (sqlite3.c:88045)
   by 0x48FD715: purple_sqlite3_get_schema_version (purplesqlite3.c:79)
   by 0x48FD9DD: purple_sqlite3_run_migrations_from_resources (purplesqlite3.c:146)
   by 0x48FDED9: purple_sqlite_history_adapter_run_migrations (purplesqlitehistoryadapter.c:69)
   by 0x48FE7F0: purple_sqlite_history_adapter_activate (purplesqlitehistoryadapter.c:287)
   by 0x48DB656: purple_history_adapter_activate (purplehistoryadapter.c:181)
   by 0x48DC9BC: purple_history_manager_set_active (purplehistorymanager.c:308)
   by 0x402BA8: test_ui_init_history (test_ui.c:132)
   by 0x402C80: test_ui_purple_init (test_ui.c:167)
   by 0x4027BB: main (test_contact.c:88)

4,368 bytes in 1 blocks are possibly lost in loss record 3,454 of 3,457
   at 0x484386F: malloc (vg_replace_malloc.c:393)
   by 0x5235B67: sqlite3MemMalloc.lto_priv.0 (sqlite3.c:25493)
   by 0x5232797: UnknownInlinedFun (sqlite3.c:29181)
   by 0x5232797: UnknownInlinedFun (sqlite3.c:29227)
   by 0x5232797: sqlite3Malloc.lto_priv.0 (sqlite3.c:29221)
   by 0x523BD8B: pcache1Alloc.lto_priv.0 (sqlite3.c:53546)
   by 0x5240077: UnknownInlinedFun (sqlite3.c:53634)
   by 0x5240077: pcache1FetchStage2 (sqlite3.c:54104)
   by 0x5243E9C: UnknownInlinedFun (sqlite3.c:52671)
   by 0x5243E9C: getPageNormal.lto_priv.0 (sqlite3.c:60628)
   by 0x52499BC: UnknownInlinedFun (sqlite3.c:60805)
   by 0x52499BC: UnknownInlinedFun (sqlite3.c:70289)
   by 0x52499BC: btreeGetUnusedPage (sqlite3.c:70432)
   by 0x524F504: allocateBtreePage.lto_priv.0 (sqlite3.c:74604)
   by 0x5256209: btreeCreateTable.lto_priv.0 (sqlite3.c:77830)
   by 0x5265EB2: UnknownInlinedFun (sqlite3.c:77849)
   by 0x5265EB2: sqlite3VdbeExec.lto_priv.0 (sqlite3.c:96382)
   by 0x525CBEE: UnknownInlinedFun (sqlite3.c:87995)
   by 0x525CBEE: UnknownInlinedFun (sqlite3.c:88056)
   by 0x525CBEE: sqlite3_step (sqlite3.c:88045)
   by 0x529B324: sqlite3_exec (sqlite3.c:131002)
   by 0x48FD558: purple_sqlite3_run_migration (purplesqlite3.c:37)
   by 0x48FDBB4: purple_sqlite3_run_migrations_from_resources (purplesqlite3.c:195)
   by 0x48FDED9: purple_sqlite_history_adapter_run_migrations (purplesqlitehistoryadapter.c:69)
   by 0x48FE7F0: purple_sqlite_history_adapter_activate (purplesqlitehistoryadapter.c:287)
   by 0x48DB656: purple_history_adapter_activate (purplehistoryadapter.c:181)
   by 0x48DC9BC: purple_history_manager_set_active (purplehistorymanager.c:308)
   by 0x402BA8: test_ui_init_history (test_ui.c:132)
   by 0x402C80: test_ui_purple_init (test_ui.c:167)
   by 0x4027BB: main (test_contact.c:88)

Ran tests in valgrind, and all above leaks were gone except for noted protocol_xfer issues, and a bunch of leaks of the PurpleBuddy-PurpleContact compatibility bindings, which will go away in their entirety eventually.