Make output deterministic for graphql interfaces (#209)

We noticed that the output from genqlient can be non-deterministic when a graphql query queries a field that's an interface. This PR fixes that by sorting the types as soon as we extract them from the schema.
Khan · Jul 28, 2022 · 2ae8ea4 · 2ae8ea4
1 parent 03b6b6b
commit 2ae8ea4
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diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
@@ -26,6 +26,8 @@ When releasing a new version:
 
 ### Bug fixes:
 
+- Fixed non-deterministic generated code when querying graphql interfaces
+
 ## v0.5.0
 
 Version 0.5.0 adds several new configuration options and convenience features. Note that genqlient now requires Go 1.16 or higher, and is tested through Go 1.18.

diff --git a/generate/convert.go b/generate/convert.go
@@ -11,6 +11,7 @@ package generate
 
 import (
 	"fmt"
+	"sort"
 
 	"github.com/vektah/gqlparser/v2/ast"
 )
@@ -465,6 +466,8 @@ func (g *generator) convertDefinition(
 		}
 
 		implementationTypes := g.schema.GetPossibleTypes(def)
+		// Make sure we generate stable output by sorting the types by name when we get them
+		sort.Slice(implementationTypes, func(i, j int) bool { return implementationTypes[i].Name < implementationTypes[j].Name })
 		goType := &goInterfaceType{
 			GoName:          name,
 			SharedFields:    sharedFields,

diff --git a/...a/snapshots/TestGenerate-ComplexInlineFragments.graphql-ComplexInlineFragments.graphql.go b/...a/snapshots/TestGenerate-ComplexInlineFragments.graphql-ComplexInlineFragments.graphql.go
diff --git a/...ata/snapshots/TestGenerate-ComplexNamedFragments.graphql-ComplexNamedFragments.graphql.go b/...ata/snapshots/TestGenerate-ComplexNamedFragments.graphql-ComplexNamedFragments.graphql.go