dev: Add round-trip test for Recurser collection (#64)

I want to be able to experiment with Pairing Bot locally, which means I'll need
some way to run Firestore without also running all of Google Cloud. It turns
out that there's an [emulator] inside of `gcloud` which is made exactly for
this purpose!

[emulator]: https://cloud.google.com/firestore/docs/emulator

The Firestore Go SDK we're using automatically supports using this via the
`FIRESTORE_EMULATOR_HOST` environment variable.

## Changes

This sets up a single round-trip test to prove that this all works. I left
space to add more because I'll be collecting them in the future as I learn
about how Firestore works (and how we use it!).

I also made these tests run on PRs to the `dev` branch. I intend to treat them
as non-blocking there, but I do think it's nice to know that we've broken unit
tests before deploying, even if it's just to the test bot.

I also added a `dev.sh` script to help me remember how to start the emulator.
It uses the same variable as the SDK so something like
[direnv](https://direnv.net/) makes it "just work".

.github/workflows/go.yml

@@ -2,9 +2,10 @@ name: Go
 
 on:
   push:
-    branches: [ main ]
+    branches:
+      - main
+      - dev
   pull_request:
-    branches: [ main ]
 
 jobs:
 
@@ -21,5 +22,20 @@ jobs:
     - name: Build
       run: go build -v ./...
 
+    - uses: google-github-actions/setup-gcloud@v2
+      with:
+        version: '>= 486.0.0'
+        install_components: 'cloud-firestore-emulator'
+
+    - name: Start Firestore emulator
+      run: |
+        gcloud emulators firestore start --host-port=[::1]:8410 &
+
+        until curl '[::1]:8410' 2>/dev/null; do
+            sleep 1
+        done
+
     - name: Test
       run: go test -v ./...
+      env:
+        FIRESTORE_EMULATOR_HOST: '[::1]:8410'

database_test.go

@@ -0,0 +1,113 @@
+package main
+
+import (
+	"context"
+	"crypto/rand"
+	"fmt"
+	"maps"
+	"math/big"
+	"testing"
+
+	"cloud.google.com/go/firestore"
+)
+
+func fakeProjectID(t *testing.T) string {
+	return fmt.Sprintf("fake-project-%d", randInt64(t))
+}
+
+func randInt64(t *testing.T) int64 {
+	int64Max := int64(1<<63 - 1)
+
+	n, err := rand.Int(rand.Reader, big.NewInt(int64Max))
+	if err != nil {
+		t.Fatal(err)
+	}
+	return n.Int64()
+}
+
+func testFirestoreClient(t *testing.T, ctx context.Context, projectID string) *firestore.Client {
+	client, err := firestore.NewClient(ctx, projectID)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Cleanup(func() {
+		if err := client.Close(); err != nil {
+			t.Logf("Error closing Firestore client: %v", err)
+		}
+	})
+
+	return client
+}
+
+func TestFirestoreRecurserDB(t *testing.T) {
+	t.Run("round-trip new recurser", func(t *testing.T) {
+		ctx := context.Background()
+		projectID := fakeProjectID(t)
+
+		client := testFirestoreClient(t, ctx, projectID)
+		recursers := &FirestoreRecurserDB{client}
+
+		recurser := Recurser{
+			id:                 randInt64(t),
+			name:               "Your Name",
+			email:              "[email protected]",
+			isSkippingTomorrow: false,
+			schedule: map[string]any{
+				"monday":    false,
+				"tuesday":   false,
+				"wednesday": false,
+				"thursday":  false,
+				"friday":    false,
+				"saturday":  false,
+				"sunday":    false,
+			},
+			isSubscribed:  false,
+			currentlyAtRC: false,
+		}
+
+		err := recursers.Set(ctx, recurser.id, recurser)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		// GetByUserID forces isSubscribed to be `true`, because that's implied by
+		// the record's existence in the DB in the first place.
+		expected := recurser
+		expected.isSubscribed = true
+
+		// GetByUserID can update the name and email address if our record is stale.
+		// These values are the same, so this call *does not* trigger that update.
+		unchanged, err := recursers.GetByUserID(ctx, recurser.id, recurser.email, recurser.name)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if !unchanged.Equal(expected) {
+			t.Errorf("values not equal:\nactual:   %+v\nexpected: %+v", unchanged, expected)
+		}
+
+		// These values are different, so this call *does* trigger an update.
+		changed, err := recursers.GetByUserID(ctx, recurser.id, "[email protected]", "My Name")
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expected.email = "[email protected]"
+		expected.name = "My Name"
+
+		if !changed.Equal(expected) {
+			t.Errorf("values not equal:\nactual:   %+v\nexpected: %+v", unchanged, expected)
+		}
+	})
+}
+
+func (r Recurser) Equal(s Recurser) bool {
+	return r.id == s.id &&
+		r.name == s.name &&
+		r.email == s.email &&
+		r.isSkippingTomorrow == s.isSkippingTomorrow &&
+		maps.Equal(r.schedule, s.schedule) &&
+		r.isSubscribed == s.isSubscribed &&
+		r.currentlyAtRC == s.currentlyAtRC
+}

dev.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+exec gcloud emulators firestore start --host-port="$FIRESTORE_EMULATOR_HOST"