feat: add HTTP link checker and GitHub GraphQL repo checker

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/checker/http_test.go

@@ -0,0 +1,80 @@
+package checker
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestCheckLinkOK(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	result := CheckLink(server.URL, &http.Client{})
+	if !result.OK {
+		t.Errorf("expected OK, got status %d, error: %s", result.StatusCode, result.Error)
+	}
+}
+
+func TestCheckLink404(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer server.Close()
+
+	result := CheckLink(server.URL, &http.Client{})
+	if result.OK {
+		t.Error("expected not OK for 404")
+	}
+	if result.StatusCode != 404 {
+		t.Errorf("status = %d, want 404", result.StatusCode)
+	}
+}
+
+func TestCheckLinkRedirect(t *testing.T) {
+	final := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer final.Close()
+
+	redir := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Redirect(w, r, final.URL, http.StatusMovedPermanently)
+	}))
+	defer redir.Close()
+
+	result := CheckLink(redir.URL, &http.Client{})
+	if !result.OK {
+		t.Errorf("expected OK after following redirect, error: %s", result.Error)
+	}
+	if !result.Redirected {
+		t.Error("expected Redirected = true")
+	}
+}
+
+func TestCheckLinks(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/bad" {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	urls := []string{server.URL + "/good", server.URL + "/bad", server.URL + "/also-good"}
+	results := CheckLinks(urls, 2, nil)
+	if len(results) != 3 {
+		t.Fatalf("results = %d, want 3", len(results))
+	}
+
+	for _, r := range results {
+		if r.URL == server.URL+"/bad" && r.OK {
+			t.Error("expected /bad to not be OK")
+		}
+		if r.URL == server.URL+"/good" && !r.OK {
+			t.Error("expected /good to be OK")
+		}
+	}
+}