Fetch independent weather sources concurrently

internal/adapters/weatherapi/client_test.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -115,6 +116,175 @@ func TestFetchBundleFromFixtures(t *testing.T) {
 	}
 }
 
+func TestFetchBundleMergesConcurrentSourcesInSourceOrder(t *testing.T) {
+	paths := []string{
+		"/observations",
+		"/forecast/hourly",
+		"/forecast/narrative",
+		"/alerts/active",
+		"/discussion",
+		"/weatherstories/latest",
+		convectiveOutlooksEndpoint,
+	}
+	started := make(chan string, len(paths))
+	release := make(map[string]chan struct{}, len(paths))
+	for _, path := range paths {
+		release[path] = make(chan struct{})
+	}
+	var releaseOnce sync.Once
+	releaseAll := func() {
+		releaseOnce.Do(func() {
+			for i := len(paths) - 1; i >= 0; i-- {
+				close(release[paths[i]])
+			}
+		})
+	}
+	t.Cleanup(releaseAll)
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == currentConditionsEndpoint {
+			if !serveWeatherFixture(w, r) {
+				http.NotFound(w, r)
+			}
+			return
+		}
+		ready, ok := release[r.URL.Path]
+		if !ok {
+			http.NotFound(w, r)
+			return
+		}
+		started <- r.URL.Path
+		<-ready
+		if !serveWeatherFixture(w, r) {
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+	client := newTestClient(t, server.URL+"/", nil)
+
+	type fetchResult struct {
+		bundle *weatherdata.Bundle
+		err    error
+	}
+	result := make(chan fetchResult, 1)
+	go func() {
+		bundle, err := client.FetchBundle(context.Background())
+		result <- fetchResult{bundle: bundle, err: err}
+	}()
+
+	seen := make(map[string]bool, len(paths))
+	for range paths {
+		select {
+		case path := <-started:
+			seen[path] = true
+		case <-time.After(time.Second):
+			t.Fatalf("independent requests started = %v, want %v", seen, paths)
+		}
+	}
+	releaseAll()
+
+	select {
+	case got := <-result:
+		if got.err != nil {
+			t.Fatalf("FetchBundle() error = %v", got.err)
+		}
+		wantSources := []string{
+			config.MissingSourceObservations,
+			config.MissingSourceCurrent,
+			"hourly",
+			config.MissingSourceNarrative,
+			config.MissingSourceAlerts,
+			config.MissingSourceDiscussion,
+			config.MissingSourceWeatherStory,
+			sourceSPCConvectiveOutlooks,
+		}
+		gotSources := make([]string, 0, len(got.bundle.Sources))
+		for _, source := range got.bundle.Sources {
+			gotSources = append(gotSources, source.Name)
+		}
+		if strings.Join(gotSources, ",") != strings.Join(wantSources, ",") {
+			t.Fatalf("source order = %v, want %v", gotSources, wantSources)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("FetchBundle() did not finish after all source responses were released")
+	}
+}
+
+func TestFetchBundleReportsConcurrentFailuresInSourceOrder(t *testing.T) {
+	var requested []string
+	server := fixtureServer(t, map[string]handlerOverride{
+		"/forecast/hourly":    {status: http.StatusBadRequest, body: `invalid hourly request`},
+		"/forecast/narrative": {status: http.StatusBadRequest, body: `invalid narrative request`},
+	}, &requested)
+	client := newTestClient(t, server.URL+"/", nil)
+
+	_, err := client.FetchBundle(context.Background())
+	if err == nil {
+		t.Fatal("FetchBundle() error = nil, want source error")
+	}
+	if !strings.Contains(err.Error(), "/forecast/hourly") {
+		t.Fatalf("error = %q, want the earlier hourly source failure", err.Error())
+	}
+	if !containsPath(requested, "/forecast/narrative") {
+		t.Fatalf("requested paths = %v, want independent narrative request", requested)
+	}
+}
+
+func TestFetchBundleCancelsConcurrentSourceRequests(t *testing.T) {
+	paths := []string{
+		"/observations",
+		"/forecast/hourly",
+		"/forecast/narrative",
+		"/alerts/active",
+		"/discussion",
+		"/weatherstories/latest",
+		convectiveOutlooksEndpoint,
+	}
+	started := make(chan string, len(paths))
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == currentConditionsEndpoint {
+			if !serveWeatherFixture(w, r) {
+				http.NotFound(w, r)
+			}
+			return
+		}
+		for _, path := range paths {
+			if r.URL.Path == path {
+				started <- path
+				<-r.Context().Done()
+				return
+			}
+		}
+		http.NotFound(w, r)
+	}))
+	defer server.Close()
+	client := newTestClient(t, server.URL+"/", nil)
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	result := make(chan error, 1)
+	go func() {
+		_, err := client.FetchBundle(ctx)
+		result <- err
+	}()
+	for range paths {
+		select {
+		case <-started:
+		case <-time.After(time.Second):
+			cancel()
+			t.Fatal("not all independent requests started before cancellation")
+		}
+	}
+	cancel()
+	select {
+	case err := <-result:
+		if err == nil || !strings.Contains(err.Error(), context.Canceled.Error()) {
+			t.Fatalf("FetchBundle() error = %v, want context cancellation", err)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("FetchBundle() did not return after cancellation")
+	}
+}
+
 func TestFetchBundleRejectsInvalidHourlyPrecipitationProbability(t *testing.T) {
 	for _, probability := range []string{"-1", "101"} {
 		t.Run(probability, func(t *testing.T) {
@@ -369,8 +539,8 @@ func TestFetchRejectsOversizedResponseWithoutRetry(t *testing.T) {
 	if narrativeCalls != 1 {
 		t.Fatalf("narrative calls = %d, want no retry", narrativeCalls)
 	}
-	if containsPath(requested, "/alerts/active") {
-		t.Fatalf("requested paths = %v, want source failure before later fetches", requested)
+	if !containsPath(requested, "/alerts/active") {
+		t.Fatalf("requested paths = %v, want independent source requests despite narrative failure", requested)
 	}
 }
 
@@ -912,21 +1082,34 @@ type handlerOverride struct {
 	handler http.HandlerFunc
 }
 
+var weatherFixtureFiles = map[string]string{
+	"/observations":            "observations.json",
+	"/conditions/current":      "current.json",
+	"/forecast/hourly":         "hourly.json",
+	"/forecast/narrative":      "narrative.json",
+	"/alerts/active":           "alerts.json",
+	"/discussion":              "discussion.json",
+	"/weatherstories/latest":   "weather_story.json",
+	convectiveOutlooksEndpoint: "convective_outlooks.json",
+}
+
+func serveWeatherFixture(w http.ResponseWriter, r *http.Request) bool {
+	name, ok := weatherFixtureFiles[r.URL.Path]
+	if !ok {
+		return false
+	}
+	http.ServeFile(w, r, filepath.Join("testdata", name))
+	return true
+}
+
 func fixtureServer(t *testing.T, overrides map[string]handlerOverride, requested *[]string) *httptest.Server {
 	t.Helper()
-	fixtures := map[string]string{
-		"/observations":            "observations.json",
-		"/conditions/current":      "current.json",
-		"/forecast/hourly":         "hourly.json",
-		"/forecast/narrative":      "narrative.json",
-		"/alerts/active":           "alerts.json",
-		"/discussion":              "discussion.json",
-		"/weatherstories/latest":   "weather_story.json",
-		convectiveOutlooksEndpoint: "convective_outlooks.json",
-	}
+	var requestedMu sync.Mutex
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if requested != nil {
+			requestedMu.Lock()
 			*requested = append(*requested, r.URL.String())
+			requestedMu.Unlock()
 		}
 		if override, ok := overrides[r.URL.Path]; ok {
 			if override.handler != nil {
@@ -937,12 +1120,9 @@ func fixtureServer(t *testing.T, overrides map[string]handlerOverride, requested
 			_, _ = w.Write([]byte(override.body))
 			return
 		}
-		name, ok := fixtures[r.URL.Path]
-		if !ok {
+		if !serveWeatherFixture(w, r) {
 			http.NotFound(w, r)
-			return
 		}
-		http.ServeFile(w, r, filepath.Join("testdata", name))
 	}))
 	t.Cleanup(server.Close)
 	return server