Your code is versioned and kept. Its runs are thrown away. CodeInstances records a run with every HTTP and HTTPS exchange it makes, then replays it offline and tells you whether it came out the same, or puts two runs side by side to show where a failing one went wrong.
10 of 10
Offline replays that matched the recording, with the live servers stopped
23 calls
HTTPS and HTTP exchanges recorded in 58 ms and kept in one 20,617-byte file
35 to 47 ms
Time for each of the 10 replays, never opening a connection
77 tests
Go tests passing, with the race detector finding nothing
From the self-checking demo and test suite of v0.3.0, recorded on a Linux machine with an Intel Xeon at 2.10GHz and 2 CPUs. The result files are in the code repository under test/results.
release
CodeInstances v0.1.0 is out. It’s a small command-line tool that keeps a run of any program as a file and replays it later, with the network replaced by what was …
release
CodeInstances v0.2.0 is out, and it adds the third verb. The first release could keep a run and replay it. This one compares two of them: codeinstances diff …
release
CodeInstances v0.3.0 adds two verbs at once. codeinstances shrink takes a failing run and a passing one and finds which of the failing run’s answers actually cause …
case studies
You maintain a command-line tool that talks to an online service. An issue comes in: “sync breaks against our account”. You don’t have their account. …
case studies
Here’s a situation most teams know. An integration test fails about one run in twenty. It calls an API that usually answers one way and occasionally answers another …
testing
A tool that claims to replay runs exactly has to be tested on exactly that. So most of the testing for v0.1.0 does the same thing over and over in different ways: record …
case studies
Some APIs you can’t call as often as you’d like. A payments sandbox that throttles you after a burst. A maps or weather API billed per request. A …
case studies
An agent ran overnight on a batch of tasks. In the morning one result is wrong. It filed a ticket under the wrong customer, or summarised a document it never fetched, or …
case studies
You need to bump something underneath your program. A new major version of the HTTP client library, a vendor’s SDK, or the Go toolchain itself. The changelog is …
Download the binary, put codeinstances record in front of a command and replay it with the network off. Questions and bug reports are welcome.