cmd/mbf: proof-of-concept CI servicedevelop

This accepts CI work over a shared read-only cache directory. This
replaces the nix CI service and prepares the removal of nix from the
test infrastructure.

Signed-off-by: Ophestra <cat@gensokyo.uk>

1 files changed, 55 insertions, 0 deletions

diff --git a/cmd/mbf/internal/ci/ci_test.go b/cmd/mbf/internal/ci/ci_test.go
new file mode 100644
index 00000000..b5ed134e
--- /dev/null
+++ b/cmd/mbf/internal/ci/ci_test.go
@@ -0,0 +1,55 @@
+package ci_test
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"hakurei.app/cmd/mbf/internal/ci"
+)
+
+func TestFollow(t *testing.T) {
+	t.Parallel()
+
+	pathname := filepath.Join(t.TempDir(), "f")
+	w, err := os.Create(pathname)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var buf bytes.Buffer
+	ctx, cancel := context.WithCancel(t.Context())
+
+	var want string
+	go func() {
+		defer cancel()
+		for _, s := range []string{
+			"\xde\xad\xbe\xef",
+			"\xff\xff\xff\xff",
+			"\x00\x00",
+		} {
+			want += s
+			if _, _err := w.WriteString(s); _err != nil {
+				panic(_err)
+			}
+		}
+	}()
+
+retry:
+	if err = ci.Follow(ctx, pathname, &buf); err != nil {
+		t.Fatal(err)
+	}
+	<-ctx.Done()
+
+	// the inotify event takes time to arrive, and there is no way to
+	// synchronise for this cleanly
+	if buf.Len() != len(want) {
+		goto retry
+	}
+
+	if got := buf.String(); got != want {
+		t.Fatalf("follow: %q, want %q", got, want)
+	}
+}