meta: cross-compile tests for other geese

For now this is just darwin/windows, but we'll eventually add support
for {free,open}bsd

Signed-off-by: evalexpr <wilkinsphysics@gmail.com>

test.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+function remove_test_files {
+    rm -f ./*test{,.exe}
+}
+
+function fail {
+    printf '%s\n' "$1" >&2
+    # If we fail, clean up after ourselves
+    remove_test_files
+    exit 1
+}
+
+function main {
+    test_dirs=()
+    while IFS= read -r -d '' file
+    do
+        dir=$(dirname "$file")
+        if [[ ! " ${test_dirs[*]} " =~ ${dir} ]]; then
+            test_dirs+=("$dir")
+        fi
+    done <   <(find . -type f -iname '*_test.go' -print0)
+
+    for goos in openbsd darwin windows
+    do
+        for dir in "${test_dirs[@]}"; do
+            echo "Testing GOOS=$goos in dir $dir"
+            GOOS="$goos" go test -c "./$dir" || fail "Test failed using $goos and $dir"
+        done
+    done
+
+    # If all goes well, we should still clean up the test files
+    echo "Test complete"
+    remove_test_files
+}
+
+main "$@"
+