README
¶
Snapshotter
Snapshotter makes it easy to write tests that verify complex test output. To
write a snapshot test, make a testhelpers.Snapshotter at the beginning of
the test, set up a call to Verify() and call Snapshot(name, value)
whenever you want to test a complex output. For example:
func TestWithComplexOutput(t *testing.T) {
snapshotter := snapshotter.New(t)
defer snapshotter.Verify()
output := DoSomethingComplicated()
snapshotter.Snapshot("complicated", output)
}
After writing the test, you can run it using go test .. However, the test
will fail, because the snapshot isn't there yet, with an error like
--- FAIL: TestSnapshotter (0.00s)
snapshotter.go:89: error reading snapshots: open testdata/TestSnapshotter.snapshots.json: no such file or directory
To generate the snapshots, run go test . -rewriteSnapshots. This generates
a set of snapshots files in the testdata directory that should be added to git.
Then, the tests will pass. If it at some point a regression causes the test
output to break, the snapshotter will catch the changes and fail:
--- FAIL: TestSnapshotter (0.00s)
snapshotter.go:116: snapshot second differs:
[
2,
{
- Foo: "Bar",
+ Foo: "Foo",
},
]
Happy testing!
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Snapshotter ¶
type Snapshotter struct {
SnapshotErrors bool
// contains filtered or unexported fields
}
Snapshotter is a utility for writing snapshot tests. In a snapshot, the expected test output is generated by running the test and storing the output, which for complex test outputs would otherwise require a lot of effort to write.
func New ¶
func New(t T) *Snapshotter
New creates a new Snapshotter. Any errors encountered will fail the test.
func NewNamed ¶
func NewNamed(t T, name string) *Snapshotter
func (*Snapshotter) Snapshot ¶
func (s *Snapshotter) Snapshot(name string, values ...interface{})
Snapshot records a value for a snapshot test. For the test to pass, all invocations to Snapshot should have the same arguments. All values should be JSON-marshalable.
func (*Snapshotter) Verify ¶
func (s *Snapshotter) Verify()
Verify finishes a snapshot test. It either compares the test output, or it rewrites the test output.
Source Files