make complement (mostly) work again

Well, kinda. It crashed on me after 10 minutes because the tests timed
out like in <https://github.com/matrix-org/complement/issues/394>.
Sounds like this means it's a them problem though.

I want to use Nix to build this image instead in the future but this
will at least make it work for now and give me a reference for while I'm
porting it. I also want to make Conduit natively understand Complement's
requirements instead of `sed`ing a bunch of stuff and needing a reverse
proxy in the container. Should be more reliable that way.

I'm not making this run in CI until the above stuff is addressed and
until I can decide on a way to pin the revision of Complement being
tested against.

from: https://gitlab.com/famedly/conduit/-/merge_requests/575

Signed-off-by: strawberry <strawberry@puppygock.gay>

bin/complement

@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+# Path to Complement's source code
+COMPLEMENT_SRC="$1"
+
+# A `.jsonl` file to write test logs to
+LOG_FILE="$2"
+
+# A `.jsonl` file to write test results to
+RESULTS_FILE="$3"
+
+OCI_IMAGE="complement-conduit:dev"
+
+env \
+    -C "$(git rev-parse --show-toplevel)" \
+    docker build \
+        --tag "$OCI_IMAGE" \
+        --file complement/Dockerfile \
+        .
+
+# It's okay (likely, even) that `go test` exits nonzero
+set +o pipefail
+env \
+    -C "$COMPLEMENT_SRC" \
+    COMPLEMENT_BASE_IMAGE="$OCI_IMAGE" \
+    go test -json ./tests | tee "$LOG_FILE"
+set -o pipefail
+
+# Post-process the results into an easy-to-compare format
+cat "$LOG_FILE" | jq -c '
+    select(
+        (.Action == "pass" or .Action == "fail" or .Action == "skip")
+        and .Test != null
+    ) | {Action: .Action, Test: .Test}
+    ' | sort > "$RESULTS_FILE"