Add --no-create-golden-file flag to run-tests.sh

This flag makes run-tests.sh not create golden files when they are
missing. This is useful when iterating on a new test so the golden
file doesn't need to be reset every time.

run-tests.sh

@@ -22,16 +22,18 @@ bootstrap=0
 safe=0
 fast=0
 compile_only=0
+create_golden_file=1 # Create golden files by default
 shell="$SHELL" # Use current shell as the default
 pattern=".*"
 while [ $# -gt 0 ]; do
   case $1 in
-    --shell)         shell="$2";         shift 2;;
-    --match)         pattern="$2";       shift 2;;
-    --bootstrap)     bootstrap=1;        shift 1;;
-    --safe)          safe=1;             shift 1;;
-    --fast)          fast=1;             shift 1;;
-    --compile-only)  compile_only=1;     shift 1;;
+    --shell)                  shell="$2";         shift 2;;
+    --match)                  pattern="$2";       shift 2;;
+    --bootstrap)              bootstrap=1;        shift 1;;
+    --safe)                   safe=1;             shift 1;;
+    --fast)                   fast=1;             shift 1;;
+    --compile-only)           compile_only=1;     shift 1;;
+    --no-create-golden-file)  create_golden_file=0;     shift 1;;
     *) echo "Unknown option: $1"; exit 1;;
   esac
 done
@@ -247,7 +249,9 @@ run_test() { # file_to_test: $1
       $dir/$filename-gcc.$ext $(test_args $file) > "$dir/$filename-gcc.output"
       if diff "$dir/$filename-gcc.output" "$dir/$filename.output"; then
         echo "🟡 Golden file generated by pnut"
-        cp "$dir/$filename.output" "$golden_file"
+        if [ "$create_golden_file" -eq 1 ]; then
+          cp "$dir/$filename.output" "$golden_file"
+        fi
       else
         echo "❌ Program compiled by gcc and pnut produced different outputs"
       fi
@@ -282,7 +286,7 @@ run_test() { # file_to_test: $1
     chmod +x "$dir/$filename.$ext"
     execute_test "$dir/$filename.$ext" "$(test_timeout $file)" "$(test_args $file)" > "$dir/$filename.output" 2> "$dir/$filename.err"
     if [ $? -eq 0 ]; then # If the executable ran successfully
-      diff_out=$(diff "$dir/$filename.output" "$dir/$filename.golden")
+      diff_out=$(diff "$dir/$filename.output" "$golden_file")
       if [ $? -eq 0 ]; then # If the output matches the golden file
         echo "✅ Test passed"
         return 0