Documentation
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Overview ¶
Package snap is a minimal file-snapshot testing helper: Match compares a string against a snapshot stored under __snapshots__/ next to the calling test file, and Clean (wired via TestMain) removes snapshots no test uses anymore. In-house replacement for the subset of go-snaps that lstk uses.
Workflow: a missing snapshot is created on the first local run (never in CI, where it fails instead). On a mismatch the test fails with a diff; UPDATE_SNAPS=true go test ./... rewrites snapshots and lets Clean delete obsolete ones.
Storage is one archive per test file (__snapshots__/<test_file>.snap) with one section per Match call:
[TestName_1] value --- [TestName_2] ...
N is the Match call number within the test. A value's newlines are stored verbatim; the "---" terminator always sits on its own line, so a value not ending in a newline gets one — a snapshot therefore cannot distinguish a value from the same value plus one final newline. The format has no escaping: a value containing a line that is exactly "---" cannot be stored; write guards against that with a parse round-trip and fails with guidance to sanitize the value instead.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
func Clean ¶
Clean runs the package's tests and then handles obsolete snapshots: archive entries no Match call used, and whole .snap archives in visited snapshot directories that no test touched. They are deleted when UPDATE_SNAPS=true, otherwise reported as an error (non-zero exit) so stale snapshots can't linger unnoticed. Wire it in TestMain:
func TestMain(m *testing.M) { os.Exit(snap.Clean(m)) }
Cleanup is skipped on failed or filtered runs (-run/-skip), where "not visited" doesn't mean obsolete.
func Match ¶
Match compares got against the stored snapshot for the calling test, creating the snapshot on first local run or rewriting it when UPDATE_SNAPS=true.
func MatchJSON ¶
MatchJSON snapshots got (a JSON document) in canonical pretty-printed form (two-space indent, object keys sorted by encoding/json), after replacing the values at the given dotted paths (e.g. "data.currentVersion") with the placeholder "<any>". Use the paths to mask values that legitimately change between runs. A path that doesn't resolve fails the test, so a masked field disappearing is caught rather than silently ignored. Paths traverse JSON objects only; there is no array-index syntax.
Types ¶
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Source Files