ci: use diff instead of git diff for the CI validation checks of the generated files (#491)

* use diff instead of git diff for the CI validation checks of the generated files

* copy only generated files to diff

Makefile

@@ -126,9 +126,9 @@ test-style:
 	@scripts/validate-go.sh
 
 .PHONY: validate-generated
-validate-generated: generate
+validate-generated:
 	@echo "==> Checking generated files <=="
-	! git diff --name-only pkg/ | grep _generated.go
+	@scripts/validate-generated.sh
 
 .PHONY: test-e2e
 test-e2e:

scripts/validate-generated.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+
+####################################################
+SOURCE="${BASH_SOURCE[0]}"
+while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
+  DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
+  SOURCE="$(readlink "$SOURCE")"
+  [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
+done
+DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
+ROOT="${DIR}/.."
+####################################################
+
+set -x
+
+GENERATED_FILES=(
+	"pkg/i18n/translations_generated.go"
+	"pkg/engine/templates_generated.go"
+)
+
+T="$(mktemp -d)"
+trap "rm -rf ${T}" EXIT
+
+for file in ${GENERATED_FILES[*]}; do
+	cp -a "${file}" "${T}/"
+done
+
+(go generate ../...)
+
+for file in ${GENERATED_FILES[*]}; do
+	basefile="$(basename ${file})"
+	if ! diff -r "${T}/${basefile}" "${ROOT}/${file}" 2>&1 ; then
+		echo "go generate produced changes that were not already present."
+		echo "Make sure you include generated assets in your commit."
+		exit 1
+	fi
+done
+
+echo "Generated assets have no material difference than what is committed."