diff --git a/test/mirror.bats b/test/mirror.bats
new file mode 100644
index 00000000..9c4615ff
--- /dev/null
+++ b/test/mirror.bats
@@ -0,0 +1,98 @@
+#!/usr/bin/env bats
+
+load test_helper
+export RUBY_BUILD_SKIP_MIRROR=
+export RUBY_BUILD_CACHE_PATH=
+export RUBY_BUILD_MIRROR_URL=http://mirror.example.com
+
+
+@test "package URL without checksum bypasses mirror" {
+  stub md5 true
+  stub curl "-*S* http://example.com/* : cat package-1.0.0.tar.gz"
+
+  install_fixture definitions/without-checksum
+  [ "$status" -eq 0 ]
+  [ -x "${INSTALL_ROOT}/bin/package" ]
+
+  unstub curl
+  unstub md5
+}
+
+
+@test "package URL with checksum but no MD5 support bypasses mirror" {
+  stub md5 false
+  stub curl "-*S* http://example.com/* : cat package-1.0.0.tar.gz"
+
+  install_fixture definitions/with-checksum
+  [ "$status" -eq 0 ]
+  [ -x "${INSTALL_ROOT}/bin/package" ]
+
+  unstub curl
+  unstub md5
+}
+
+
+@test "package URL with checksum hits mirror first" {
+  local checksum="83e6d7725e20166024a1eb74cde80677"
+  local mirror_url="${RUBY_BUILD_MIRROR_URL}/$checksum"
+
+  stub md5 true "echo $checksum"
+  stub curl "-*I* $mirror_url : true" "-*S* $mirror_url : cat package-1.0.0.tar.gz"
+
+  install_fixture definitions/with-checksum
+  [ "$status" -eq 0 ]
+  [ -x "${INSTALL_ROOT}/bin/package" ]
+
+  unstub curl
+  unstub md5
+}
+
+
+@test "package is fetched from original URL if mirror download fails" {
+  local checksum="83e6d7725e20166024a1eb74cde80677"
+  local mirror_url="${RUBY_BUILD_MIRROR_URL}/$checksum"
+  local original_url="http://example.com/packages/package-1.0.0.tar.gz"
+
+  stub md5 true "echo $checksum"
+  stub curl "-*I* $mirror_url : false" "-*S* $original_url : cat package-1.0.0.tar.gz"
+
+  install_fixture definitions/with-checksum
+  [ "$status" -eq 0 ]
+  [ -x "${INSTALL_ROOT}/bin/package" ]
+
+  unstub curl
+  unstub md5
+}
+
+
+@test "package is fetched from original URL if mirror download checksum is invalid" {
+  local checksum="83e6d7725e20166024a1eb74cde80677"
+  local mirror_url="${RUBY_BUILD_MIRROR_URL}/$checksum"
+  local original_url="http://example.com/packages/package-1.0.0.tar.gz"
+
+  stub md5 true "echo invalid" "echo $checksum"
+  stub curl "-*I* $mirror_url : true" "-*S* $mirror_url : cat package-1.0.0.tar.gz" "-*S* $original_url : cat package-1.0.0.tar.gz"
+
+  install_fixture definitions/with-checksum
+  [ "$status" -eq 0 ]
+  [ -x "${INSTALL_ROOT}/bin/package" ]
+
+  unstub curl
+  unstub md5
+}
+
+
+@test "default mirror URL" {
+  export RUBY_BUILD_MIRROR_URL=
+  local checksum="83e6d7725e20166024a1eb74cde80677"
+
+  stub md5 true "echo $checksum"
+  stub curl "-*I* : true" "-*S* http://?*/$checksum : cat package-1.0.0.tar.gz"
+
+  install_fixture definitions/with-checksum
+  [ "$status" -eq 0 ]
+  [ -x "${INSTALL_ROOT}/bin/package" ]
+
+  unstub curl
+  unstub md5
+}