Ben KraftandGitHub
f4c981031e
## Summary: When genqlient generates output types, it generates whatever code is necessary to unmarshal them. Conversely, when it generates input types, it generates whatever code is necessary to marshal. This is all that's needed for genqlient itself: it never needs to marshal output types or unmarshal input types. But maybe you do! (For example, to put the responses in a cache, which is the use case that @csilvers hit at Khan, although there are others one can imagine.) While we can't support every serialization format you might want (at least not without adding plugins or some such), it's not unreasonable to expect that since genqlient can read JSON, it can write it too. Sadly, in the past this was not true for types requiring custom unmarshaling logic, for several reasons. In this commit I implement logic to always write both marshalers and unmarshalers whenever they're needed to be able to correctly round-trip the types, even though genqlient doesn't do so. I wasn't starting from scratch, since of course we already write both marshalers and unmarshalers in some cases. But this ended up requiring surprisingly large changes on the marshaling side, mostly to correctly support embedding (which we use for named fragments). Specifically, as the comments in `types.go` discuss, the most difficult issue is spreads with duplicate fields, which translate to Go embedded fields which end up hidden from the json-marshaler. Ultimately, I had to do things quite differently from unmarshaling, and essentially flatten the type when we write marshaler. But in the end it's not so ugly -- indeed arguably it's cleaner! Mainly it's just different. One thing to note is that we do marshal `__typename` based on what we know about the types; users need not fill it in (and if they do we'll ignore it). This seemed to me to be a better UX, and didn't add much complexity. In general, I begin to wonder whether using `encoding/json` at all is really right for genqlient: we're doing a lot of work to appease it, despite knowing what our types look like. I think it would still be a significant increase in lines of code to roll our own, but that code would perhaps be simpler, and would surely be faster (although if we just want the speed gains we could use another JSON-generator library, see also #47). Anyway, something to think about in the future. ## Test plan: make tesc Author: benjaminjkraft Reviewers: csilvers, StevenACoffman, benjaminjkraft, dnerdy, aberkan, jvoll, mahtabsabet, MiguelCastillo Required Reviewers: Approved By: StevenACoffman, dnerdy Checks: ✅ Test (1.17), ✅ Test (1.16), ✅ Test (1.15), ✅ Test (1.14), ✅ Lint, ✅ Test (1.17), ✅ Test (1.16), ✅ Test (1.15), ✅ Test (1.14), ✅ Lint Pull Request URL: https://github.com/Khan/genqlient/pull/120
112 lines
3.0 KiB
Go
112 lines
3.0 KiB
Go
package integration
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// Machinery for integration tests to round-trip check the JSON-marshalers and
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// unmarshalers we generate.
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import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"io/ioutil"
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"net/http"
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"testing"
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"github.com/Khan/genqlient/graphql"
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"github.com/stretchr/testify/assert"
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)
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// lastResponseTransport is an HTTP transport that keeps track of the last response
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// that passed through it.
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type lastResponseTransport struct {
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wrapped http.RoundTripper
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lastResponseBody []byte
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}
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func (t *lastResponseTransport) RoundTrip(req *http.Request) (*http.Response, error) {
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resp, err := t.wrapped.RoundTrip(req)
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if err != nil {
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return resp, err
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}
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defer resp.Body.Close()
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return resp, fmt.Errorf("roundtrip failed: unreadable body: %w", err)
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}
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t.lastResponseBody = body
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// Restore the body for the next reader:
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resp.Body = ioutil.NopCloser(bytes.NewBuffer(body))
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return resp, err
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}
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// roundtripClient is a graphql.Client that checks that
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// unmarshal(marshal(req)) == req && marshal(unmarshal(resp)) == resp
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// for each request it processes.
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type roundtripClient struct {
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wrapped graphql.Client
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transport *lastResponseTransport
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t *testing.T
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}
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// Put JSON in a stable and human-readable format.
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func (c *roundtripClient) formatJSON(b []byte) []byte {
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// We don't care about key ordering, so do another roundtrip through
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// interface{} to drop that.
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var parsed interface{}
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err := json.Unmarshal(b, &parsed)
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if err != nil {
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c.t.Fatal(err)
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}
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// When marshaling, add indents to make things human-readable.
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b, err = json.MarshalIndent(parsed, "", " ")
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if err != nil {
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c.t.Fatal(err)
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}
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return b
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}
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func (c *roundtripClient) roundtripResponse(resp interface{}) {
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var graphqlResponse struct {
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Data json.RawMessage `json:"data"`
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}
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err := json.Unmarshal(c.transport.lastResponseBody, &graphqlResponse)
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if err != nil {
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c.t.Error(err)
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return
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}
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body := c.formatJSON(graphqlResponse.Data)
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// resp is constructed to be unmarshal(body), so just use it
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bodyAgain, err := json.Marshal(resp)
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if err != nil {
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c.t.Error(err)
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return
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}
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bodyAgain = c.formatJSON(bodyAgain)
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assert.Equal(c.t, string(body), string(bodyAgain))
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}
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func (c *roundtripClient) MakeRequest(ctx context.Context, opName, query string, retval, variables interface{}) error {
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// TODO(benkraft): Also check the variables round-trip. This is a bit less
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// important since most of the code is the same (and input types are
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// strictly simpler), and a bit hard to do because when asserting about
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// structs we need to worry about things like equality of time.Time values.
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err := c.wrapped.MakeRequest(ctx, opName, query, retval, variables)
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if err != nil {
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return err
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}
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c.roundtripResponse(retval)
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return nil
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}
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func newRoundtripClient(t *testing.T, endpoint string) graphql.Client {
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transport := &lastResponseTransport{wrapped: http.DefaultTransport}
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return &roundtripClient{
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wrapped: graphql.NewClient(endpoint, &http.Client{Transport: transport}),
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transport: transport,
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t: t,
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}
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}
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