Add telemetry package

Author: adrianpk

docs/features.md

@@ -14,7 +14,7 @@
 |---------|-------------|
 | `web` | Chi router helpers, response utilities, flash messages |
 | `htmx` | HTMX primitives (triggers, actions, targets, swaps), response headers, template helpers |
-| `middleware` | Request ID, role-based access, rate limiting, locale detection, static cache |
+| `middleware` | Request ID, role-based access, rate limiting, locale detection, static cache, telemetry |
 | `render` | Template FuncMap utilities, i18n integration |
 | `ui` | UI kit with HTMX-first components (Chip, Label, Button, Alert, Flash, Toast, Link, Form, Table, Nav) |
 | `format` | Formatting utilities (Price, Number) for templates |
@@ -55,6 +55,7 @@
 |---------|-------------|
 | `mailer` | Email delivery (SMTP, SendGrid, AWS SES) |
 | `pubsub` | Publish/subscribe messaging |
+| `telemetry` | Request counting, crash collection, settings schemas |
 | `testhelper` | Testing utilities |
-| `fake` | Test doubles (mailer) |
+| `fake` | Test doubles (mailer, telemetry) |
 

fake/telemetry.go

@@ -0,0 +1,168 @@
+package fake
+
+import "sync"
+
+// CounterCall records an IncrementRequests call.
+type CounterCall struct{}
+
+// Counter is a test double for telemetry.RequestCounter.
+type Counter struct {
+	mu sync.Mutex
+
+	IncrementFunc   func()
+	incrementCalls  []CounterCall
+	GetAndResetFunc func() int64
+	getAndResetCalls int
+	simulatedCount  int64
+}
+
+// NewCounter creates a new fake Counter.
+func NewCounter() *Counter {
+	return &Counter{}
+}
+
+// IncrementRequests records the call and invokes IncrementFunc if set.
+func (c *Counter) IncrementRequests() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.incrementCalls = append(c.incrementCalls, CounterCall{})
+	c.simulatedCount++
+
+	if c.IncrementFunc != nil {
+		c.IncrementFunc()
+	}
+}
+
+// GetAndResetRequests returns simulatedCount and resets it, or calls GetAndResetFunc if set.
+func (c *Counter) GetAndResetRequests() int64 {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.getAndResetCalls++
+
+	if c.GetAndResetFunc != nil {
+		return c.GetAndResetFunc()
+	}
+
+	count := c.simulatedCount
+	c.simulatedCount = 0
+	return count
+}
+
+// Reset clears all recorded calls and the simulated count.
+func (c *Counter) Reset() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.incrementCalls = nil
+	c.getAndResetCalls = 0
+	c.simulatedCount = 0
+}
+
+// IncrementCount returns the number of IncrementRequests calls.
+func (c *Counter) IncrementCount() int {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return len(c.incrementCalls)
+}
+
+// GetAndResetCount returns the number of GetAndResetRequests calls.
+func (c *Counter) GetAndResetCount() int {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.getAndResetCalls
+}
+
+// WithCount sets the simulated count and returns the Counter for chaining.
+func (c *Counter) WithCount(n int64) *Counter {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.simulatedCount = n
+	return c
+}
+
+// CrashCall records a RecordPanic call.
+type CrashCall struct {
+	Message  string
+	Endpoint string
+	Method   string
+}
+
+// CrashCollector is a test double for telemetry.CrashRecorder.
+type CrashCollector struct {
+	mu sync.Mutex
+
+	RecordPanicFunc func(message, endpoint, method string)
+	calls           []CrashCall
+}
+
+// NewCrashCollector creates a new fake CrashCollector.
+func NewCrashCollector() *CrashCollector {
+	return &CrashCollector{}
+}
+
+// RecordPanic records the call and invokes RecordPanicFunc if set.
+func (c *CrashCollector) RecordPanic(message, endpoint, method string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.calls = append(c.calls, CrashCall{
+		Message:  message,
+		Endpoint: endpoint,
+		Method:   method,
+	})
+
+	if c.RecordPanicFunc != nil {
+		c.RecordPanicFunc(message, endpoint, method)
+	}
+}
+
+// Reset clears all recorded calls.
+func (c *CrashCollector) Reset() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.calls = nil
+}
+
+// RecordCount returns the number of RecordPanic calls.
+func (c *CrashCollector) RecordCount() int {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return len(c.calls)
+}
+
+// LastRecord returns the most recent CrashCall or nil if none.
+func (c *CrashCollector) LastRecord() *CrashCall {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if len(c.calls) == 0 {
+		return nil
+	}
+	call := c.calls[len(c.calls)-1]
+	return &call
+}
+
+// HasRecordFor returns true if any call was recorded for the given endpoint.
+func (c *CrashCollector) HasRecordFor(endpoint string) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	for _, call := range c.calls {
+		if call.Endpoint == endpoint {
+			return true
+		}
+	}
+	return false
+}
+
+// GetCalls returns a copy of all recorded calls.
+func (c *CrashCollector) GetCalls() []CrashCall {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	result := make([]CrashCall, len(c.calls))
+	copy(result, c.calls)
+	return result
+}