diff --git a/test/fixtures/cache-tests/results/apache.json b/test/fixtures/cache-tests/results/apache.json
index 86c732f6e36..5da2d1df2d9 100644
--- a/test/fixtures/cache-tests/results/apache.json
+++ b/test/fixtures/cache-tests/results/apache.json
@@ -423,6 +423,10 @@
   "heuristic-delta-60": true,
   "heuristic-delta-600": true,
   "heuristic-delta-86400": true,
+  "interim-102": true,
+  "interim-103": true,
+  "interim-no-header-reuse": true,
+  "interim-not-cached": true,
   "invalidate-DELETE": true,
   "invalidate-DELETE-cl": [
     "Assertion",
diff --git a/test/fixtures/cache-tests/results/caddy.json b/test/fixtures/cache-tests/results/caddy.json
index d45ef15d4a9..b9bcb867da0 100644
--- a/test/fixtures/cache-tests/results/caddy.json
+++ b/test/fixtures/cache-tests/results/caddy.json
@@ -537,6 +537,22 @@
     "Assertion",
     "Response 2 does not come from cache"
   ],
+  "interim-102": [
+    "Assertion",
+    "Interim response 1 not received"
+  ],
+  "interim-103": [
+    "Assertion",
+    "Interim response 1 not received"
+  ],
+  "interim-no-header-reuse": [
+    "Assertion",
+    "Interim response 1 not received"
+  ],
+  "interim-not-cached": [
+    "Assertion",
+    "Interim response 1 not received"
+  ],
   "invalidate-DELETE": true,
   "invalidate-DELETE-cl": [
     "Assertion",
diff --git a/test/fixtures/cache-tests/results/haproxy.json b/test/fixtures/cache-tests/results/haproxy.json
new file mode 100644
index 00000000000..9b30c981005
--- /dev/null
+++ b/test/fixtures/cache-tests/results/haproxy.json
@@ -0,0 +1,859 @@
+{
+  "304-etag-update-response-Cache-Control": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Clear-Site-Data": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Content-Encoding": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Content-Foo": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Content-Length": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Content-Location": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Content-MD5": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Content-Range": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Content-Security-Policy": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Content-Type": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-ETag": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Expires": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Public-Key-Pins": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Set-Cookie": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Set-Cookie2": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-Test-Header": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-X-Content-Foo": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-X-Frame-Options": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-X-Test-Header": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-etag-update-response-X-XSS-Protection": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "304-lm-use-stored-Test-Header": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "age-parse-dup-0": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "age-parse-dup-0-twoline": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "age-parse-dup-old": true,
+  "age-parse-float": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "age-parse-large": true,
+  "age-parse-large-minus-one": true,
+  "age-parse-larger": true,
+  "age-parse-negative": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "age-parse-nonnumeric": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "age-parse-numeric-parameter": true,
+  "age-parse-parameter": true,
+  "age-parse-prefix": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "age-parse-prefix-twoline": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "age-parse-suffix": true,
+  "age-parse-suffix-twoline": true,
+  "cc-resp-must-revalidate-fresh": true,
+  "cc-resp-must-revalidate-stale": [
+    "Assertion",
+    "Request 3 should have been conditional, but it was not."
+  ],
+  "cc-resp-no-cache": true,
+  "cc-resp-no-cache-case-insensitive": true,
+  "cc-resp-no-cache-revalidate": [
+    "Assertion",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "cc-resp-no-cache-revalidate-fresh": [
+    "Assertion",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "cc-resp-no-store": true,
+  "cc-resp-no-store-case-insensitive": true,
+  "cc-resp-no-store-fresh": true,
+  "cc-resp-no-store-old-max-age": true,
+  "cc-resp-no-store-old-new": true,
+  "cc-resp-private-shared": true,
+  "ccreq-ma0": true,
+  "ccreq-ma1": true,
+  "ccreq-magreaterage": [
+    "Setup",
+    "Response 1 header Age is \"null\", not \"1800\""
+  ],
+  "ccreq-max-stale": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "ccreq-max-stale-age": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "ccreq-min-fresh": true,
+  "ccreq-min-fresh-age": [
+    "Setup",
+    "Response 1 header Age is \"null\", not \"1000\""
+  ],
+  "ccreq-no-cache": true,
+  "ccreq-no-cache-etag": [
+    "Assertion",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "ccreq-no-cache-lm": [
+    "Assertion",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "ccreq-no-store": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "ccreq-oic": [
+    "Assertion",
+    "Response 1 status is 200, not 504"
+  ],
+  "cdn-cc-invalid-sh-type-unknown": true,
+  "cdn-cc-invalid-sh-type-wrong": [
+    "AbortError",
+    "This operation was aborted"
+  ],
+  "cdn-date-update-exceed": true,
+  "cdn-expires-update-exceed": [
+    "Assertion",
+    "Response 2 header Expires is \"null\", not \"Wed, 12 Mar 2025 10:13:52 GMT\""
+  ],
+  "cdn-fresh-cc-nostore": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age-0": true,
+  "cdn-max-age-0-expires": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "cdn-max-age-age": true,
+  "cdn-max-age-case-insensitive": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age-cc-max-age-invalid-expires": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age-expires": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age-extension": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age-long-cc-max-age": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "cdn-max-age-max": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age-max-plus": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age-short-cc-max-age": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "cdn-max-age-space-after-equals": true,
+  "cdn-max-age-space-before-equals": true,
+  "cdn-no-cache": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "cdn-no-store-cc-fresh": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "cdn-private": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "cdn-remove-age-exceed": [
+    "Assertion",
+    "Response 2 Age header not present."
+  ],
+  "cdn-remove-header": true,
+  "conditional-304-etag": true,
+  "conditional-etag-forward": true,
+  "conditional-etag-forward-unquoted": [
+    "Assertion",
+    "Request 1 header If-None-Match is \"abcdef\", not \"\"abcdef\"\""
+  ],
+  "conditional-etag-precedence": true,
+  "conditional-etag-quoted-respond-unquoted": [
+    "Assertion",
+    "Response 2 status is 200, not 304"
+  ],
+  "conditional-etag-strong-generate": [
+    "Assertion",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "conditional-etag-strong-generate-unquoted": [
+    "Assertion",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "conditional-etag-strong-respond": true,
+  "conditional-etag-strong-respond-multiple-first": true,
+  "conditional-etag-strong-respond-multiple-last": true,
+  "conditional-etag-strong-respond-multiple-second": true,
+  "conditional-etag-strong-respond-obs-text": [
+    "Assertion",
+    "Response 2 status is 200, not 304"
+  ],
+  "conditional-etag-unquoted-respond-quoted": [
+    "Assertion",
+    "Response 2 status is 200, not 304"
+  ],
+  "conditional-etag-unquoted-respond-unquoted": [
+    "Assertion",
+    "Response 2 status is 200, not 304"
+  ],
+  "conditional-etag-vary-headers": [
+    "Setup",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "conditional-etag-vary-headers-mismatch": true,
+  "conditional-etag-weak-generate-weak": [
+    "Assertion",
+    "Request 2 should have been conditional, but it was not."
+  ],
+  "conditional-etag-weak-respond": true,
+  "conditional-etag-weak-respond-backslash": [
+    "Assertion",
+    "Response 2 status is 200, not 304"
+  ],
+  "conditional-etag-weak-respond-lowercase": [
+    "Assertion",
+    "Response 2 status is 200, not 304"
+  ],
+  "conditional-etag-weak-respond-omit-slash": [
+    "Assertion",
+    "Response 2 status is 200, not 304"
+  ],
+  "conditional-lm-fresh": true,
+  "conditional-lm-fresh-earlier": true,
+  "conditional-lm-fresh-no-lm": [
+    "Assertion",
+    "Response 2 status is 200, not 304"
+  ],
+  "conditional-lm-fresh-rfc850": true,
+  "conditional-lm-stale": true,
+  "freshness-expires-32bit": true,
+  "freshness-expires-age-fast-date": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "freshness-expires-age-slow-date": true,
+  "freshness-expires-ansi-c": true,
+  "freshness-expires-far-future": true,
+  "freshness-expires-future": true,
+  "freshness-expires-invalid": true,
+  "freshness-expires-invalid-1-digit-hour": true,
+  "freshness-expires-invalid-2-digit-year": true,
+  "freshness-expires-invalid-aest": true,
+  "freshness-expires-invalid-date": true,
+  "freshness-expires-invalid-date-dashes": true,
+  "freshness-expires-invalid-multiple-lines": true,
+  "freshness-expires-invalid-multiple-spaces": true,
+  "freshness-expires-invalid-no-comma": true,
+  "freshness-expires-invalid-time-periods": true,
+  "freshness-expires-invalid-utc": true,
+  "freshness-expires-old-date": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "freshness-expires-past": true,
+  "freshness-expires-present": true,
+  "freshness-expires-rfc850": true,
+  "freshness-expires-wrong-case-month": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "freshness-expires-wrong-case-tz": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "freshness-expires-wrong-case-weekday": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "freshness-max-age": true,
+  "freshness-max-age-0": true,
+  "freshness-max-age-0-expires": true,
+  "freshness-max-age-100a": true,
+  "freshness-max-age-a100": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "freshness-max-age-age": true,
+  "freshness-max-age-case-insenstive": true,
+  "freshness-max-age-date": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "freshness-max-age-decimal-five": true,
+  "freshness-max-age-decimal-zero": true,
+  "freshness-max-age-expires": true,
+  "freshness-max-age-expires-invalid": true,
+  "freshness-max-age-extension": true,
+  "freshness-max-age-ignore-quoted": true,
+  "freshness-max-age-ignore-quoted-rev": true,
+  "freshness-max-age-leading-zero": true,
+  "freshness-max-age-max": true,
+  "freshness-max-age-max-minus-1": true,
+  "freshness-max-age-max-plus": true,
+  "freshness-max-age-max-plus-1": true,
+  "freshness-max-age-negative": true,
+  "freshness-max-age-quoted": true,
+  "freshness-max-age-s-maxage-shared-longer": true,
+  "freshness-max-age-s-maxage-shared-longer-multiple": true,
+  "freshness-max-age-s-maxage-shared-longer-reversed": true,
+  "freshness-max-age-s-maxage-shared-shorter": true,
+  "freshness-max-age-s-maxage-shared-shorter-expires": true,
+  "freshness-max-age-single-quoted": true,
+  "freshness-max-age-space-after-equals": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "freshness-max-age-space-before-equals": [
+    "Assertion",
+    "Response 2 comes from cache"
+  ],
+  "freshness-max-age-stale": true,
+  "freshness-max-age-two-fresh-stale-sameline": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "freshness-max-age-two-fresh-stale-sepline": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "freshness-max-age-two-stale-fresh-sameline": true,
+  "freshness-max-age-two-stale-fresh-sepline": true,
+  "freshness-none": true,
+  "freshness-s-maxage-shared": true,
+  "head-200-freshness-update": [
+    "Assertion",
+    "Response 3 does not come from cache"
+  ],
+  "head-200-retain": [
+    "Assertion",
+    "Response 2 header Template-A is \"null\", not \"1\""
+  ],
+  "head-200-update": [
+    "Setup",
+    "Response 3 does not come from cache"
+  ],
+  "head-410-update": [
+    "Setup",
+    "Response 3 does not come from cache"
+  ],
+  "head-writethrough": true,
+  "headers-omit-headers-listed-in-Cache-Control-no-cache": [
+    "Assertion",
+    "Response 2 includes unexpected header a: \"1\""
+  ],
+  "headers-omit-headers-listed-in-Cache-Control-no-cache-single": [
+    "Assertion",
+    "Response 2 includes unexpected header a: \"1\""
+  ],
+  "headers-omit-headers-listed-in-Connection": [
+    "Assertion",
+    "Response 2 includes unexpected header a: \"1\""
+  ],
+  "headers-store-Cache-Control": true,
+  "headers-store-Clear-Site-Data": true,
+  "headers-store-Connection": true,
+  "headers-store-Content-Encoding": true,
+  "headers-store-Content-Foo": true,
+  "headers-store-Content-Length": true,
+  "headers-store-Content-Location": true,
+  "headers-store-Content-MD5": true,
+  "headers-store-Content-Range": true,
+  "headers-store-Content-Security-Policy": true,
+  "headers-store-Content-Type": true,
+  "headers-store-ETag": true,
+  "headers-store-Expires": true,
+  "headers-store-Keep-Alive": true,
+  "headers-store-Proxy-Authenticate": true,
+  "headers-store-Proxy-Authentication-Info": true,
+  "headers-store-Proxy-Authorization": true,
+  "headers-store-Proxy-Connection": true,
+  "headers-store-Public-Key-Pins": true,
+  "headers-store-Set-Cookie": true,
+  "headers-store-Set-Cookie2": true,
+  "headers-store-TE": true,
+  "headers-store-Test-Header": true,
+  "headers-store-Transfer-Encoding": [
+    "Setup",
+    "Response 1 status is 502, not 200"
+  ],
+  "headers-store-Upgrade": true,
+  "headers-store-X-Content-Foo": true,
+  "headers-store-X-Frame-Options": true,
+  "headers-store-X-Test-Header": true,
+  "headers-store-X-XSS-Protection": true,
+  "heuristic-200-cached": true,
+  "heuristic-201-not_cached": true,
+  "heuristic-202-not_cached": true,
+  "heuristic-203-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "heuristic-204-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "heuristic-403-not_cached": true,
+  "heuristic-404-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "heuristic-405-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "heuristic-410-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "heuristic-414-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "heuristic-501-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "heuristic-502-not_cached": true,
+  "heuristic-503-not_cached": true,
+  "heuristic-504-not_cached": true,
+  "heuristic-599-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "heuristic-599-not_cached": true,
+  "heuristic-delta-10": true,
+  "heuristic-delta-1200": true,
+  "heuristic-delta-1800": true,
+  "heuristic-delta-30": true,
+  "heuristic-delta-300": true,
+  "heuristic-delta-3600": true,
+  "heuristic-delta-43200": true,
+  "heuristic-delta-5": true,
+  "heuristic-delta-60": true,
+  "heuristic-delta-600": true,
+  "heuristic-delta-86400": true,
+  "interim-102": true,
+  "interim-103": true,
+  "interim-no-header-reuse": true,
+  "interim-not-cached": true,
+  "invalidate-DELETE": true,
+  "invalidate-DELETE-cl": [
+    "Assertion",
+    "Response 3 comes from cache"
+  ],
+  "invalidate-DELETE-failed": true,
+  "invalidate-DELETE-location": [
+    "Assertion",
+    "Response 3 comes from cache"
+  ],
+  "invalidate-M-SEARCH": true,
+  "invalidate-M-SEARCH-cl": [
+    "Assertion",
+    "Response 3 comes from cache"
+  ],
+  "invalidate-M-SEARCH-failed": true,
+  "invalidate-M-SEARCH-location": [
+    "Assertion",
+    "Response 3 comes from cache"
+  ],
+  "invalidate-POST": true,
+  "invalidate-POST-cl": [
+    "Assertion",
+    "Response 3 comes from cache"
+  ],
+  "invalidate-POST-failed": true,
+  "invalidate-POST-location": [
+    "Assertion",
+    "Response 3 comes from cache"
+  ],
+  "invalidate-PUT": true,
+  "invalidate-PUT-cl": [
+    "Assertion",
+    "Response 3 comes from cache"
+  ],
+  "invalidate-PUT-failed": true,
+  "invalidate-PUT-location": [
+    "Assertion",
+    "Response 3 comes from cache"
+  ],
+  "method-POST": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "other-age-delay": [
+    "Assertion",
+    "Response 1 age header not present."
+  ],
+  "other-age-gen": true,
+  "other-age-update-expires": [
+    "Setup",
+    "Response 1 header Age is \"null\", not \"30\""
+  ],
+  "other-age-update-max-age": [
+    "Setup",
+    "Response 1 header Age is \"null\", not \"30\""
+  ],
+  "other-authorization": true,
+  "other-authorization-must-revalidate": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "other-authorization-public": true,
+  "other-authorization-smaxage": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "other-cookie": true,
+  "other-date-update": true,
+  "other-date-update-expires": true,
+  "other-date-update-expires-update": true,
+  "other-fresh-content-disposition-attachment": true,
+  "other-heuristic-content-disposition-attachment": true,
+  "other-set-cookie": true,
+  "partial-store-complete-reuse-partial": [
+    "Assertion",
+    "Response 2 status is 200, not 206"
+  ],
+  "partial-store-complete-reuse-partial-no-last": [
+    "Assertion",
+    "Response 2 status is 200, not 206"
+  ],
+  "partial-store-complete-reuse-partial-suffix": [
+    "Assertion",
+    "Response 2 status is 200, not 206"
+  ],
+  "partial-store-partial-complete": [
+    "Assertion",
+    "Request 2 header range is \"undefined\", not \"bytes=5-\""
+  ],
+  "partial-store-partial-reuse-partial": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "partial-store-partial-reuse-partial-absent": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "partial-store-partial-reuse-partial-byterange": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "partial-store-partial-reuse-partial-suffix": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "partial-use-headers": [
+    "Setup",
+    "Response 2 status is 200, not 206"
+  ],
+  "partial-use-stored-headers": [
+    "Setup",
+    "Response 2 status is 200, not 206"
+  ],
+  "pragma-request-extension": true,
+  "pragma-request-no-cache": true,
+  "pragma-response-extension": true,
+  "pragma-response-no-cache": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "pragma-response-no-cache-heuristic": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "query-args-different": true,
+  "query-args-same": true,
+  "stale-503": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "stale-close": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-close-must-revalidate": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-close-no-cache": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-close-proxy-revalidate": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-close-s-maxage=2": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-sie-503": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-sie-close": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-warning-become": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-warning-stored": [
+    "TypeError",
+    "fetch failed"
+  ],
+  "stale-while-revalidate": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "stale-while-revalidate-window": [
+    "Setup",
+    "Response 2 does not come from cache"
+  ],
+  "status-200-fresh": true,
+  "status-200-must-understand": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-200-stale": true,
+  "status-203-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-203-stale": true,
+  "status-204-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-204-stale": true,
+  "status-299-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-299-stale": true,
+  "status-301-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-301-stale": true,
+  "status-302-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-302-stale": true,
+  "status-303-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-303-stale": true,
+  "status-307-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-307-stale": true,
+  "status-308-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-308-stale": true,
+  "status-400-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-400-stale": true,
+  "status-404-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-404-stale": true,
+  "status-410-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-410-stale": true,
+  "status-499-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-499-stale": true,
+  "status-500-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-500-stale": true,
+  "status-502-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-502-stale": true,
+  "status-503-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-503-stale": true,
+  "status-504-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-504-stale": true,
+  "status-599-fresh": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "status-599-must-understand": true,
+  "status-599-stale": true,
+  "vary-2-match": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-2-match-omit": true,
+  "vary-2-no-match": true,
+  "vary-3-match": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-3-no-match": true,
+  "vary-3-omit": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-3-order": true,
+  "vary-cache-key": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-invalidate": [
+    "Assertion",
+    "Response 3 does not come from cache"
+  ],
+  "vary-match": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-no-match": true,
+  "vary-normalise-combine": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-normalise-lang-case": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-normalise-lang-order": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-normalise-lang-select": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-normalise-lang-space": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-normalise-space": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "vary-omit": true,
+  "vary-omit-stored": true,
+  "vary-star": true,
+  "vary-syntax-empty-star": true,
+  "vary-syntax-empty-star-lines": true,
+  "vary-syntax-foo-star": true,
+  "vary-syntax-star": true,
+  "vary-syntax-star-foo": true,
+  "vary-syntax-star-star": true,
+  "vary-syntax-star-star-lines": true
+}
diff --git a/test/fixtures/cache-tests/results/index.mjs b/test/fixtures/cache-tests/results/index.mjs
index 3d1afde079f..aaa7a525a18 100644
--- a/test/fixtures/cache-tests/results/index.mjs
+++ b/test/fixtures/cache-tests/results/index.mjs
@@ -61,6 +61,13 @@ export default [
     version: '0.7.0',
     link: 'https://github.com/http-tests/cache-tests/wiki/Caddy'
   },
+  {
+    file: 'haproxy.json',
+    name: 'HAProxy',
+    type: 'rev-proxy',
+    version: '3.0.8-1ubuntu1',
+    link: 'https://github.com/http-tests/cache-tests/wiki/HAProxy'
+  },
   {
     file: 'fastly.json',
     name: 'Fastly',
diff --git a/test/fixtures/cache-tests/results/nginx.json b/test/fixtures/cache-tests/results/nginx.json
index 1f12ac9984e..c3dd75bf5a9 100644
--- a/test/fixtures/cache-tests/results/nginx.json
+++ b/test/fixtures/cache-tests/results/nginx.json
@@ -564,6 +564,22 @@
     "Assertion",
     "Response 2 does not come from cache"
   ],
+  "interim-102": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "interim-103": [
+    "AbortError",
+    "This operation was aborted"
+  ],
+  "interim-no-header-reuse": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
+  "interim-not-cached": [
+    "Assertion",
+    "Response 2 does not come from cache"
+  ],
   "invalidate-DELETE": [
     "Assertion",
     "Response 3 comes from cache"
diff --git a/test/fixtures/cache-tests/results/squid.json b/test/fixtures/cache-tests/results/squid.json
index 906f12a9013..1872efc917e 100644
--- a/test/fixtures/cache-tests/results/squid.json
+++ b/test/fixtures/cache-tests/results/squid.json
@@ -438,6 +438,10 @@
   "heuristic-delta-60": true,
   "heuristic-delta-600": true,
   "heuristic-delta-86400": true,
+  "interim-102": true,
+  "interim-103": true,
+  "interim-no-header-reuse": true,
+  "interim-not-cached": true,
   "invalidate-DELETE": true,
   "invalidate-DELETE-cl": true,
   "invalidate-DELETE-failed": true,
diff --git a/test/fixtures/cache-tests/results/trafficserver.json b/test/fixtures/cache-tests/results/trafficserver.json
index c2112d1ad18..93e49f9f8a5 100644
--- a/test/fixtures/cache-tests/results/trafficserver.json
+++ b/test/fixtures/cache-tests/results/trafficserver.json
@@ -456,6 +456,22 @@
     "Assertion",
     "Response 2 does not come from cache"
   ],
+  "interim-102": [
+    "AbortError",
+    "This operation was aborted"
+  ],
+  "interim-103": [
+    "Assertion",
+    "Interim response 1 not received"
+  ],
+  "interim-no-header-reuse": [
+    "Assertion",
+    "Interim response 1 not received"
+  ],
+  "interim-not-cached": [
+    "Assertion",
+    "Interim response 1 not received"
+  ],
   "invalidate-DELETE": [
     "Setup",
     "Response 2 status is 403, not 200"
diff --git a/test/fixtures/cache-tests/results/varnish.json b/test/fixtures/cache-tests/results/varnish.json
index 067c395fc15..75faf830bfc 100644
--- a/test/fixtures/cache-tests/results/varnish.json
+++ b/test/fixtures/cache-tests/results/varnish.json
@@ -498,6 +498,22 @@
     "Assertion",
     "Response 2 does not come from cache"
   ],
+  "interim-102": [
+    "Setup",
+    "Response 1 status is 503, not 200"
+  ],
+  "interim-103": [
+    "Setup",
+    "Response 1 status is 503, not 200"
+  ],
+  "interim-no-header-reuse": [
+    "Setup",
+    "Response 1 status is 503, not 200"
+  ],
+  "interim-not-cached": [
+    "Setup",
+    "Response 1 status is 503, not 200"
+  ],
   "invalidate-DELETE": [
     "Assertion",
     "Response 3 comes from cache"
diff --git a/test/fixtures/cache-tests/test-engine/client/test.mjs b/test/fixtures/cache-tests/test-engine/client/test.mjs
index 56487a1135f..fb08d807e42 100644
--- a/test/fixtures/cache-tests/test-engine/client/test.mjs
+++ b/test/fixtures/cache-tests/test-engine/client/test.mjs
@@ -18,7 +18,7 @@ export async function makeTest (test) {
   const fetchFunctions = []
   for (let i = 0; i < requests.length; ++i) {
     fetchFunctions.push({
-      code: idx => {
+      code: async idx => {
         const reqConfig = requests[idx]
         const reqNum = idx + 1
         const url = clientUtils.makeTestUrl(uuid, reqConfig)
@@ -32,11 +32,20 @@ export async function makeTest (test) {
           controller.abort()
         }, config.requestTimeout * 1000)
         init.signal = controller.signal
+
+        const interimResponses = []
+        if ('expected_interim_responses' in reqConfig) {
+          // Dynamic import since undici is only available in Node.js
+          const undici = await import('undici')
+          const dispatcher = new undici.Agent().compose(clientUtils.interimResponsesCollectingInterceptor(interimResponses))
+          init.dispatcher = dispatcher
+        }
+
         if (test.dump === true) clientUtils.logRequest(url, init, reqNum)
         return fetch(url, init)
           .then(response => {
             responses.push(response)
-            return checkResponse(test, requests, idx, response)
+            return checkResponse(test, requests, idx, response, interimResponses)
           })
           .finally(() => {
             clearTimeout(timeout)
@@ -84,11 +93,11 @@ export async function makeTest (test) {
     })
 }
 
-function checkResponse (test, requests, idx, response) {
+function checkResponse (test, requests, idx, response, interimResponses) {
   const reqNum = idx + 1
   const reqConfig = requests[idx]
   const resNum = parseInt(response.headers.get('Server-Request-Count'))
-  if (test.dump === true) clientUtils.logResponse(response, reqNum)
+  if (test.dump === true) clientUtils.logResponse(response, interimResponses, reqNum)
 
   // catch retries
   if (response.headers.has('Request-Numbers')) {
@@ -185,6 +194,37 @@ function checkResponse (test, requests, idx, response) {
       }
     })
   }
+
+  // check interim responses
+  if ('expected_interim_responses' in reqConfig) {
+    const isSetup = setupCheck(reqConfig, 'expected_interim_responses')
+
+    reqConfig.expected_interim_responses.forEach(([statusCode, headers = []], idx) => {
+      if (interimResponses[idx] == null) {
+        assert(isSetup, false, `Interim response ${idx + 1} not received`)
+      } else {
+        assert(isSetup, interimResponses[idx][0] === statusCode, `Interim response ${idx + 1} status is ${interimResponses[idx][0]}, not ${statusCode}`)
+
+        const receivedHeaders = interimResponses[idx][1]
+        headers.forEach(([header, value]) => {
+          if (typeof header === 'string') {
+            assert(isSetup, header in receivedHeaders,
+              `Interim response ${idx + 1} ${header} header not present.`)
+          } else if (header.length > 2) {
+            assert(isSetup, header in receivedHeaders,
+              `Interim response ${idx + 1} ${header} header not present.`)
+
+            const receivedValue = receivedHeaders[header]
+            assert(isSetup, value === receivedValue,
+              `Interim response ${idx + 1} header ${header} is ${receivedValue}, should ${value}`)
+          } else {
+            console.log('ERROR: Unknown header item in expected_interim_responses', header)
+          }
+        })
+      }
+    })
+  }
+
   return response.text().then(makeCheckResponseBody(test, reqConfig, response.status))
 }
 
diff --git a/test/fixtures/cache-tests/test-engine/client/utils.mjs b/test/fixtures/cache-tests/test-engine/client/utils.mjs
index 21d918d1e98..a23f3e9fa63 100644
--- a/test/fixtures/cache-tests/test-engine/client/utils.mjs
+++ b/test/fixtures/cache-tests/test-engine/client/utils.mjs
@@ -72,11 +72,61 @@ export function logRequest (url, init, reqNum) {
   console.log('')
 }
 
-export function logResponse (response, reqNum) {
+export function logResponse (response, interimResponses, reqNum) {
   console.log(`${defines.GREEN}=== Client response ${reqNum}${defines.NC}`)
+  for (const [statusCode, headers] of interimResponses) {
+    console.log(`    HTTP ${statusCode}`)
+    for (const [key, value] of Object.entries(headers)) {
+      console.log(`    ${key}: ${value}`)
+    }
+    console.log('')
+  }
   console.log(`    HTTP ${response.status} ${response.statusText}`)
   response.headers.forEach((hvalue, hname) => { // for some reason, node-fetch reverses these
     console.log(`    ${hname}: ${hvalue}`)
   })
   console.log('')
 }
+
+class InterimResponsesCollectingHandler {
+  #handler
+  #interimResponses
+
+  constructor (handler, interimResponses) {
+    this.#handler = handler
+    this.#interimResponses = interimResponses
+  }
+
+  onRequestStart (controller, context) {
+    this.#handler.onRequestStart?.(controller, context)
+  }
+
+  onRequestUpgrade (controller, statusCode, headers, socket) {
+    this.#handler.onRequestUpgrade?.(controller, statusCode, headers, socket)
+  }
+
+  onResponseStart (controller, statusCode, headers, statusMessage) {
+    if (statusCode < 200) this.#interimResponses.push([statusCode, headers])
+    this.#handler.onResponseStart?.(controller, statusCode, headers, statusMessage)
+  }
+
+  onResponseData (controller, data) {
+    this.#handler.onResponseData?.(controller, data)
+  }
+
+  onResponseEnd (controller, trailers) {
+    this.#handler.onResponseEnd?.(controller, trailers)
+  }
+
+  onResponseError (controller, err) {
+    this.#handler.onResponseError?.(controller, err)
+  }
+}
+
+export function interimResponsesCollectingInterceptor (collectInto) {
+  return (dispatch) => {
+    return (opts, handler) => {
+      return dispatch(opts, new InterimResponsesCollectingHandler(handler, collectInto))
+    }
+  }
+}
diff --git a/test/fixtures/cache-tests/test-engine/lib/testsuite-schema.json b/test/fixtures/cache-tests/test-engine/lib/testsuite-schema.json
index 95294ff81a6..1890c8da543 100644
--- a/test/fixtures/cache-tests/test-engine/lib/testsuite-schema.json
+++ b/test/fixtures/cache-tests/test-engine/lib/testsuite-schema.json
@@ -133,6 +133,102 @@
                     "description": "Whether to rewrite Location and Content-Location to full URLs",
                     "type": "boolean"
                   },
+                  "interim_responses": {
+                    "description": "Interim responses to send before the final response",
+                    "type": "array",
+                    "items": {
+                      "oneOf": [
+                        {
+                          "description": "Status code only",
+                          "type": "array",
+                          "minItems": 1,
+                          "maxItems": 1,
+                          "items": [
+                            {
+                              "$ref": "#/definitions/status-code"
+                            }
+                          ]
+                        },
+                        {
+                          "description": "Status code and headers",
+                          "type": "array",
+                          "minItems": 2,
+                          "maxItems": 2,
+                          "items": [
+                            {
+                              "$ref": "#/definitions/status-code"
+                            },
+                            {
+                              "description": "Interim response headers",
+                              "type": "array",
+                              "items": {
+                                "type": "array",
+                                "additionalItems": false,
+                                "minItems": 2,
+                                "maxItems": 2,
+                                "items": [
+                                  {
+                                    "$ref": "#/definitions/field-name"
+                                  },
+                                  {
+                                    "$ref": "#/definitions/magic-field-value"
+                                  }
+                                ]
+                              }
+                            }
+                          ]
+                        }
+                      ]
+                    }
+                  },
+                  "expected_interim_responses": {
+                    "description": "Interim responses expected to be received by the client",
+                    "type": "array",
+                    "items": {
+                      "oneOf": [
+                        {
+                          "description": "Status code only",
+                          "type": "array",
+                          "minItems": 1,
+                          "maxItems": 1,
+                          "items": [
+                            {
+                              "$ref": "#/definitions/status-code"
+                            }
+                          ]
+                        },
+                        {
+                          "description": "Status code and headers",
+                          "type": "array",
+                          "minItems": 2,
+                          "maxItems": 2,
+                          "items": [
+                            {
+                              "$ref": "#/definitions/status-code"
+                            },
+                            {
+                              "description": "Expected interim response headers",
+                              "type": "array",
+                              "items": {
+                                "type": "array",
+                                "additionalItems": false,
+                                "minItems": 2,
+                                "maxItems": 2,
+                                "items": [
+                                  {
+                                    "$ref": "#/definitions/field-name"
+                                  },
+                                  {
+                                    "$ref": "#/definitions/magic-field-value"
+                                  }
+                                ]
+                              }
+                            }
+                          ]
+                        }
+                      ]
+                    }
+                  },
                   "magic_ims": {
                     "description": "Whether to rewrite If-Modified-Since to a delta from the previous Last-Modified",
                     "type": "boolean"
diff --git a/test/fixtures/cache-tests/test-engine/lib/tpl/checks.liquid b/test/fixtures/cache-tests/test-engine/lib/tpl/checks.liquid
index 730290f5d81..0193a06367d 100644
--- a/test/fixtures/cache-tests/test-engine/lib/tpl/checks.liquid
+++ b/test/fixtures/cache-tests/test-engine/lib/tpl/checks.liquid
@@ -7,6 +7,13 @@
 
 ### The following checks will be performed:
 
+{%- if request.interim_responses -%}
+{%- for interim_response in request.interim_responses %}
+- The client will check that an interim response with the `{{ interim_response[0] }}` status code{% if interim_response[1] %} and the following headers{% endif %} is received.
+{%- render 'header-list' with interim_response[1] as headers %}
+{%- endfor -%}
+{%- endif -%}
+
 {%- if request.expected_type %}
 - The client will check that this response {% case request.expected_type %}{% when "cached" %}is cached{% when "not_cached" %}is not cached{% when "lm_validated" %}is validated using `Last-Modified`{% when "etag_validated" %}is validated using `ETag`{% endcase %} {% if test.setup_tests contains "expected_type" %}{{ setup_prop }}{% endif %}{% endif -%}
 
diff --git a/test/fixtures/cache-tests/test-engine/lib/tpl/explain-test.liquid b/test/fixtures/cache-tests/test-engine/lib/tpl/explain-test.liquid
index 975a6ceedfa..c791ab023c6 100644
--- a/test/fixtures/cache-tests/test-engine/lib/tpl/explain-test.liquid
+++ b/test/fixtures/cache-tests/test-engine/lib/tpl/explain-test.liquid
@@ -62,8 +62,16 @@ The server will pause for {{ request.response_pause }} seconds before responding
 
 {%- if request.response_status or request.response_headers or request.response_body %}
 
-### The server sends a response containing:
+### The server sends {% if request.interim_responses %}responses{% else %}a response{% endif %} containing:
+
 ~~~
+{% if request.interim_responses -%}
+{% for interim_response in request.interim_responses -%}
+HTTP/1.1 {{ interim_response[0] }}
+{% for header in interim_response[1] %}{% render 'header-magic' with header as header %}
+{% endfor %}
+{% endfor -%}
+{%- endif -%}
 {% if request.expected_type == "lm_validated" or request.expected_type = "etag_validated" -%}
 HTTP/1.1 304 Not Modified
 {%- else -%}
diff --git a/test/fixtures/cache-tests/test-engine/server/handle-test.mjs b/test/fixtures/cache-tests/test-engine/server/handle-test.mjs
index 13aae63bee6..808020469eb 100644
--- a/test/fixtures/cache-tests/test-engine/server/handle-test.mjs
+++ b/test/fixtures/cache-tests/test-engine/server/handle-test.mjs
@@ -43,6 +43,17 @@ function continueHandleTest (uuid, request, response, requests, serverState) {
   const previousConfig = requests[reqNum - 2]
   const now = Date.now()
 
+  const interimResponses = reqConfig.interim_responses || []
+  for (const [status, headers = []] of interimResponses) {
+    if (status === 102) {
+      response.writeProcessing()
+    } else if (status === 103) {
+      response.writeEarlyHints(Object.fromEntries(headers))
+    } else {
+      console.log(`ERROR: Sending ${status} is not yet supported`)
+    }
+  }
+
   // Determine what the response status should be
   let httpStatus = reqConfig.response_status || [200, 'OK']
   if ('expected_type' in reqConfig && reqConfig.expected_type.endsWith('validated')) {
@@ -114,5 +125,5 @@ function continueHandleTest (uuid, request, response, requests, serverState) {
   }
 
   // logging
-  if (reqConfig.dump) logResponse(response, srvReqNum)
+  if (reqConfig.dump) logResponse(response, interimResponses, srvReqNum)
 }
diff --git a/test/fixtures/cache-tests/test-engine/server/utils.mjs b/test/fixtures/cache-tests/test-engine/server/utils.mjs
index 7f37a665313..ce496a86116 100644
--- a/test/fixtures/cache-tests/test-engine/server/utils.mjs
+++ b/test/fixtures/cache-tests/test-engine/server/utils.mjs
@@ -40,11 +40,18 @@ export function logRequest (request, reqNum) {
   console.log('')
 }
 
-export function logResponse (response, resNum) {
+export function logResponse (response, interimResponses, resNum) {
   console.log(`${BLUE}=== Server response ${resNum}${NC}`)
   if (response === 'disconnect') {
     console.log('    [ server disconnect ]')
   } else {
+    for (const [statusCode, headers] of interimResponses) {
+      console.log(`    HTTP ${statusCode}`)
+      for (const [key, value] of headers) {
+        console.log(`    ${key}: ${value}`)
+      }
+      console.log('')
+    }
     console.log(`    HTTP ${response.statusCode} ${response.statusPhrase}`)
     for (const [key, value] of Object.entries(response.getHeaders())) {
       console.log(`    ${key}: ${value}`)
diff --git a/test/fixtures/cache-tests/tests/index.mjs b/test/fixtures/cache-tests/tests/index.mjs
index 3b7378c1537..1a79eff426f 100644
--- a/test/fixtures/cache-tests/tests/index.mjs
+++ b/test/fixtures/cache-tests/tests/index.mjs
@@ -22,5 +22,6 @@ import partial from './partial.mjs'
 import auth from './authorization.mjs'
 import other from './other.mjs'
 import cdncc from './cdn-cache-control.mjs'
+import interim from './interim.mjs'
 
-export default [ccFreshness, ccParse, ageParse, expires, expiresParse, ccResponse, stale, heuristic, methods, statuses, ccRequest, pragma, vary, varyParse, conditionalLm, conditionalEtag, headers, update304, updateHead, invalidation, partial, auth, other, cdncc]
+export default [ccFreshness, ccParse, ageParse, expires, expiresParse, ccResponse, stale, heuristic, methods, statuses, ccRequest, pragma, vary, varyParse, conditionalLm, conditionalEtag, headers, update304, updateHead, invalidation, partial, auth, other, cdncc, interim]
diff --git a/test/fixtures/cache-tests/tests/interim.mjs b/test/fixtures/cache-tests/tests/interim.mjs
new file mode 100644
index 00000000000..4ffb3139dd2
--- /dev/null
+++ b/test/fixtures/cache-tests/tests/interim.mjs
@@ -0,0 +1,124 @@
+export default
+
+{
+  name: 'Interim Response Handling',
+  id: 'interim',
+  description: 'These tests check how caches handle interim responses.',
+  tests: [
+    {
+      name: 'An optimal HTTP cache passes a 102 response through and caches the final response',
+      id: 'interim-102',
+      browser_skip: true, // Fetch API in browsers don't expose interim responses
+      kind: 'optimal',
+      requests: [
+        {
+          interim_responses: [[102]],
+          expected_interim_responses: [[102]],
+          response_headers: [
+            ['Cache-Control', 'max-age=100000'],
+            ['Date', 0]
+          ],
+          pause_after: true
+        },
+        {
+          expected_type: 'cached'
+        }
+      ]
+    },
+    {
+      name: 'An optimal HTTP cache passes a 103 response through and caches the final response',
+      id: 'interim-103',
+      browser_skip: true,
+      kind: 'optimal',
+      requests: [
+        {
+          interim_responses: [
+            [103, [
+              ['link', '</styles.css>; rel=preload; as=style'],
+              ['x-my-header', 'test']
+            ]]
+          ],
+          expected_interim_responses: [
+            [103, [
+              ['link', '</styles.css>; rel=preload; as=style'],
+              ['x-my-header', 'test']
+            ]]
+          ],
+          response_headers: [
+            ['Cache-Control', 'max-age=100000'],
+            ['Date', 0]
+          ],
+          pause_after: true
+        },
+        {
+          expected_type: 'cached'
+        }
+      ]
+    },
+    {
+      name: 'An HTTP cache should not cache non-final responses',
+      id: 'interim-not-cached',
+      browser_skip: true,
+      kind: 'required',
+      requests: [
+        {
+          interim_responses: [
+            [103, [
+              ['link', '</styles.css>; rel=preload; as=style']
+            ]]
+          ],
+          expected_interim_responses: [
+            [103, [
+              ['link', '</styles.css>; rel=preload; as=style']
+            ]]
+          ],
+          response_headers: [
+            ['Cache-Control', 'max-age=100000'],
+            ['Date', 0]
+          ],
+          pause_after: true
+        },
+        {
+          expected_type: 'cached',
+          expected_interim_responses: []
+        }
+      ]
+    },
+    {
+      name: 'An optimal HTTP cache should not store headers from non-final responses',
+      id: 'interim-no-header-reuse',
+      browser_skip: true,
+      kind: 'optimal',
+      requests: [
+        {
+          interim_responses: [
+            [103, [
+              ['link', '</styles.css>; rel=preload; as=style'],
+              ['x-my-header', 'test']
+            ]]
+          ],
+          expected_interim_responses: [
+            [103, [
+              ['link', '</styles.css>; rel=preload; as=style'],
+              ['x-my-header', 'test']
+            ]]
+          ],
+          response_headers: [
+            ['Cache-Control', 'max-age=100000'],
+            ['Date', 0]
+          ],
+          expected_response_headers_missing: [
+            'x-my-header'
+          ],
+          pause_after: true
+        },
+        {
+          expected_type: 'cached',
+          expected_response_headers_missing: [
+            'x-my-header'
+          ]
+        }
+      ]
+    }
+  ]
+}