Add eval details template for JQ

Fix stacklok/minder-stories#41

internal/engine/eval/jq/jq.go

@@ -26,6 +26,7 @@ import (
 	"google.golang.org/protobuf/reflect/protoreflect"
 
 	evalerrors "github.com/stacklok/minder/internal/engine/errors"
+	"github.com/stacklok/minder/internal/engine/eval/templates"
 	engif "github.com/stacklok/minder/internal/engine/interfaces"
 	eoptions "github.com/stacklok/minder/internal/engine/options"
 	"github.com/stacklok/minder/internal/util"
@@ -124,7 +125,16 @@ func (jqe *Evaluator) Eval(ctx context.Context, pol map[string]any, _ protorefle
 				msg = fmt.Sprintf("%s\nassertion: %s", msg, string(marshalledAssertion))
 			}
 
-			return evalerrors.NewErrEvaluationFailed("%s", msg)
+			return evalerrors.NewDetailedErrEvaluationFailed(
+				templates.JqTemplate,
+				map[string]any{
+					"path":     a.Ingested.Def,
+					"expected": expectedVal,
+					"actual":   dataVal,
+				},
+				"%s",
+				msg,
+			)
 		}
 	}
 

internal/engine/eval/jq/jq_test.go

@@ -20,10 +20,12 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"google.golang.org/protobuf/types/known/structpb"
 
 	evalerrors "github.com/stacklok/minder/internal/engine/errors"
 	"github.com/stacklok/minder/internal/engine/eval/jq"
+	"github.com/stacklok/minder/internal/engine/eval/templates"
 	engif "github.com/stacklok/minder/internal/engine/interfaces"
 	pb "github.com/stacklok/minder/pkg/api/protobuf/go/minder/v1"
 )
@@ -664,3 +666,65 @@ func TestInvalidJQEvals(t *testing.T) {
 		})
 	}
 }
+
+func TestEvaluationDetailRendering(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		msg     string
+		msgArgs []any
+		tmpl    string
+		args    any
+		error   string
+		details string
+	}{
+		// JQ template
+		{
+			name: "JQ template with different actual and expected values",
+			msg:  "this is the message",
+			tmpl: templates.JqTemplate,
+			args: map[string]any{
+				"path":     ".simple",
+				"expected": true,
+				"actual":   false,
+			},
+			error: "evaluation failure: this is the message",
+			details: "The detected configuration does not match the desired configuration:\n" +
+				"Expected \".simple\" to equal true, but was false.",
+		},
+		{
+			name: "JQ template with different actual value equal nil",
+			msg:  "this is the message",
+			tmpl: templates.JqTemplate,
+			args: map[string]any{
+				"path":     ".simple",
+				"expected": 5,
+				"actual":   nil,
+			},
+			error: "evaluation failure: this is the message",
+			details: "The detected configuration does not match the desired configuration:\n" +
+				"Expected \".simple\" to equal 5, but was not set.",
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			err := evalerrors.NewDetailedErrEvaluationFailed(
+				tt.tmpl,
+				tt.args,
+				tt.msg,
+				tt.msgArgs...,
+			)
+
+			require.Equal(t, tt.error, err.Error())
+			evalErr, ok := err.(*evalerrors.EvaluationError)
+			require.True(t, ok)
+			require.Equal(t, tt.details, evalErr.Details())
+		})
+	}
+}

internal/engine/eval/templates/jq.tmpl

@@ -0,0 +1,2 @@
+The detected configuration does not match the desired configuration:
+Expected "{{.path}}" to equal {{.expected}}, but was {{if eq .actual nil}}not set{{else}}{{.actual}}{{end}}.

internal/engine/eval/templates/templates.go

@@ -61,3 +61,10 @@ var MixedScriptsTemplate string
 //
 //go:embed invisibleCharactersTemplate.tmpl
 var InvisibleCharactersTemplate string
+
+// JqTemplate is the template for details of the `jq` evaluation engine.
+//
+// This template expects three parameters, `path`, `expected`, and `actual`, which are strings.
+//
+//go:embed jq.tmpl
+var JqTemplate string