Extract has_checksum_support predicate function

- Remove unnecessary HAS_X_SUPPORT variables
- Merge conditional for unsetting mirror-url
- Memoize has_checksum_support function

bin/ruby-build

@@ -246,6 +246,12 @@ compute_md5() {
   fi
 }
 
+declare -a HAS_CHECKSUM_SUPPORT
+has_checksum_support() {
+  local checksum_command="$1"
+  return ${HAS_CHECKSUM_SUPPORT[$checksum_command]:=$(echo test | "$checksum_command" >/dev/null; echo $?)}
+}
+
 verify_checksum() {
   local checksum_command
   local filename="$1"
@@ -255,22 +261,19 @@ verify_checksum() {
   [ -e "$filename" ] || return 0
 
   case "${#expected_checksum}" in
-  0) # If there's no expected checksum, return success
-    return 0
-    ;;
-  32) # MD5
-    [ -n "$HAS_MD5_SUPPORT" ] || return 0
-    checksum_command="compute_md5"
-    ;;
-  64) # SHA2 256
-    [ -n "$HAS_SHA2_SUPPORT" ] || return 0
-    checksum_command="compute_sha2"
-    ;;
-  *) # unknown checksum algorithm, return failure
-    return 1
-    ;;
+  # If expected checksum is empty, return success
+  0) return 0 ;;
+  # MD5
+  32) checksum_command="compute_md5" ;;
+  # SHA2 256
+  64) checksum_command="compute_sha2" ;;
+  # unknown checksum algorithm, return failure
+  *) return 1 ;;
   esac
 
+  # If chosen provided checksum algorithm isn't supported, return success
+  has_checksum_support "$checksum_command" || return 0
+
   # If the computed checksum is empty, return failure
   local computed_checksum=`echo "$($checksum_command < "$filename")" | tr [A-Z] [a-z]`
   [ -n "$computed_checksum" ] || return 1
@@ -1225,23 +1228,10 @@ else
   RUBY_BUILD_DEFAULT_MIRROR=
 fi
 
-if [ -n "$RUBY_BUILD_SKIP_MIRROR" ]; then
+if [ -n "$RUBY_BUILD_SKIP_MIRROR" ] || ! has_checksum_support compute_sha2; then
   unset RUBY_BUILD_MIRROR_URL
 fi
 
-if echo test | compute_sha2 >/dev/null; then
-  HAS_SHA2_SUPPORT=1
-else
-  unset HAS_SHA2_SUPPORT
-  unset RUBY_BUILD_MIRROR_URL
-fi
-
-if echo test | compute_md5 >/dev/null; then
-  HAS_MD5_SUPPORT=1
-else
-  unset HAS_MD5_SUPPORT
-fi
-
 SEED="$(date "+%Y%m%d%H%M%S").$$"
 LOG_PATH="${TMP}/ruby-build.${SEED}.log"
 RUBY_BIN="${PREFIX_PATH}/bin/ruby"

test/cache.bats

@@ -10,7 +10,6 @@ setup() {
 
 
 @test "packages are saved to download cache" {
-  stub shasum true
   stub curl "-q -o * -*S* http://example.com/* : cp $FIXTURE_ROOT/\${5##*/} \$3"
 
   install_fixture definitions/without-checksum
@@ -19,12 +18,10 @@ setup() {
   [ -e "${RUBY_BUILD_CACHE_PATH}/package-1.0.0.tar.gz" ]
 
   unstub curl
-  unstub shasum
 }
 
 
 @test "cached package without checksum" {
-  stub shasum true
   stub curl
 
   cp "${FIXTURE_ROOT}/package-1.0.0.tar.gz" "$RUBY_BUILD_CACHE_PATH"
@@ -35,7 +32,6 @@ setup() {
   [ -e "${RUBY_BUILD_CACHE_PATH}/package-1.0.0.tar.gz" ]
 
   unstub curl
-  unstub shasum
 }
 
 
@@ -79,7 +75,6 @@ setup() {
 
 
 @test "nonexistent cache directory is ignored" {
-  stub shasum true
   stub curl "-q -o * -*S* http://example.com/* : cp $FIXTURE_ROOT/\${5##*/} \$3"
 
   export RUBY_BUILD_CACHE_PATH="${TMP}/nonexistent"
@@ -91,5 +86,4 @@ setup() {
   [ ! -d "$RUBY_BUILD_CACHE_PATH" ]
 
   unstub curl
-  unstub shasum
 }

test/checksum.bats

@@ -6,7 +6,6 @@ export RUBY_BUILD_CACHE_PATH=
 
 
 @test "package URL without checksum" {
-  stub shasum true
   stub curl "-q -o * -*S* http://example.com/* : cp $FIXTURE_ROOT/\${5##*/} \$3"
 
   install_fixture definitions/without-checksum
@@ -14,7 +13,6 @@ export RUBY_BUILD_CACHE_PATH=
   [ -x "${INSTALL_ROOT}/bin/package" ]
 
   unstub curl
-  unstub shasum
 }