encoding/openapi: finalise when constructing openapi AST

When building OpenAPI enums from a CUE instance, specifically one that
contains an enum imported from protobuf, we don't care about the
definition-encoded integer enum value (introduced as part of dcfff00).
Instead we only care about the final value of the enum.

Prior to dcfff00, an imported protobuf enum would look like this:

    #CaptureMode: "DEFAULT" | "IPTABLES" | "NONE"

Post dcfff00, it looks like:

    #CaptureMode: {
            "DEFAULT"
            #enumValue: 0
    } | {
            "IPTABLES"
            #enumValue: 1
    } | {
            "NONE"
            #enumValue: 2
    }

Therefore, in the process of building an enum we simply need to finalise
the CUE Value prior to deriving its syntax.

The test as part of this CL comes from a real Istio schema that
uncovered this bug in the first place.

Fixes #977

Change-Id: I5b4cbb2f35b0535488d8f77b1e2166f89ed2644d
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/9843
Reviewed-by: CUE cueckoo <[email protected]>
Reviewed-by: Marcel van Lohuizen <[email protected]>

encoding/openapi/build.go

@@ -1301,10 +1301,10 @@ func (b *builder) inta(v cue.Value, offset int64) ast.Expr {
 
 func (b *builder) decode(v cue.Value) ast.Expr {
 	v, _ = v.Default()
-	return v.Syntax().(ast.Expr)
+	return v.Syntax(cue.Final()).(ast.Expr)
 }
 
 func (b *builder) big(v cue.Value) ast.Expr {
 	v, _ = v.Default()
-	return v.Syntax().(ast.Expr)
+	return v.Syntax(cue.Final()).(ast.Expr)
 }

encoding/openapi/openapi_test.go

@@ -63,6 +63,10 @@ func TestParseDefinitions(t *testing.T) {
 		"array.cue",
 		"array.json",
 		defaultConfig,
+	}, {
+		"enum.cue",
+		"enum.json",
+		defaultConfig,
 	}, {
 		"struct.cue",
 		"struct.json",
@@ -140,6 +144,12 @@ func TestParseDefinitions(t *testing.T) {
 				t.Fatal(errors.Details(inst.Err, nil))
 			}
 
+			all, err := tc.config.All(inst)
+			if err != nil {
+				t.Fatal(err)
+			}
+			walk(all)
+
 			b, err := openapi.Gen(inst, tc.config)
 			if err != nil {
 				t.Fatal(err)
@@ -165,6 +175,21 @@ func TestParseDefinitions(t *testing.T) {
 	}
 }
 
+// walk traverses an openapi.OrderedMap. This is a helper function
+// used to ensure that a generated OpenAPI value is well-formed.
+func walk(om *openapi.OrderedMap) {
+	for _, p := range om.Pairs() {
+		switch p := p.Value.(type) {
+		case *openapi.OrderedMap:
+			walk(p)
+		case []*openapi.OrderedMap:
+			for _, om := range p {
+				walk(om)
+			}
+		}
+	}
+}
+
 // This is for debugging purposes. Do not remove.
 func TestX(t *testing.T) {
 	t.Skip()

encoding/openapi/testdata/enum.cue

@@ -0,0 +1,10 @@
+#CaptureMode: {
+	"DEFAULT"
+	#enumValue: 0
+} | {
+	"IPTABLES"
+	#enumValue: 1
+} | {
+	"NONE"
+	#enumValue: 2
+}

encoding/openapi/testdata/enum.json

@@ -0,0 +1,20 @@
+{
+   "openapi": "3.0.0",
+   "info": {
+      "title": "Generated by cue.",
+      "version": "no version"
+   },
+   "paths": {},
+   "components": {
+      "schemas": {
+         "CaptureMode": {
+            "type": "string",
+            "enum": [
+               "DEFAULT",
+               "IPTABLES",
+               "NONE"
+            ]
+         }
+      }
+   }
+}