preprocess: Eliminate eval in subshell

This is part of the effort to improve performance by reducing the number
of command substitutions/subshells.

Under Bash 3.2.57(1)-release on a MacBook Pro with a 2.9GHz Intel Core
i5 CPU and 8GB 1867MHz DDR3 RAM, this shaves off O(0.15s) from the test
suite at the previous commit, but I anticipate this effect being
magnified on Windows platforms.

libexec/bats-preprocess

@@ -33,18 +33,18 @@ encode_name() {
 
 tests=()
 index=0
-pattern='^ *@test  *([^ ].*)  *\{ *(.*)$'
+pattern='^ *@test +(.+) +\{ *(.*)$'
 
 while IFS= read -r line; do
   line="${line//$'\r'}"
   let index+=1
   if [[ "$line" =~ $pattern ]]; then
-    quoted_name="${BASH_REMATCH[1]}"
+    name="${BASH_REMATCH[1]#[\'\"]}"
+    name="${name%[\'\"]}"
     body="${BASH_REMATCH[2]}"
-    name="$(eval echo "$quoted_name")"
     encode_name "$name" 'encoded_name'
     tests["${#tests[@]}"]="$encoded_name"
-    echo "${encoded_name}() { bats_test_begin ${quoted_name} ${index}; ${body}"
+    echo "${encoded_name}() { bats_test_begin \"${name}\" ${index}; ${body}"
   else
     printf "%s\n" "$line"
   fi

test/bats.bats

@@ -280,5 +280,5 @@ fixtures bats
   [ $status -eq 0 ]
   [ "${lines[1]}" = "ok 1 single-quoted name" ]
   [ "${lines[2]}" = "ok 2 double-quoted name" ]
-  [ "${lines[3]}" = "ok 3 unquoted" ]
+  [ "${lines[3]}" = "ok 3 unquoted name" ]
 }

test/fixtures/bats/quoted_and_unquoted_test_names.bats

@@ -6,6 +6,6 @@
   true
 }
 
-@test unquoted {
+@test unquoted name {
   true
 }