headers: fail Build on missing native exports and assert MI/COM layouts (#2739)

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

pkg/collector/build_error_internal_test.go

@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: Apache-2.0
+//
+// Copyright The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build windows
+
+package collector
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/prometheus-community/windows_exporter/internal/headers/lazyproc"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sys/windows"
+)
+
+// TestExpectedBuildError_MissingNativeAPI checks that a collector whose
+// binding Load fails because of a missing DLL or export is skipped, also
+// inside the joined errors of collectors with sub-collectors.
+func TestExpectedBuildError_MissingNativeAPI(t *testing.T) {
+	t.Parallel()
+
+	kernel32 := windows.NewLazySystemDLL("kernel32.dll")
+	missingDLL := windows.NewLazySystemDLL("windows_exporter_missing.dll")
+
+	missingExport := lazyproc.Find(kernel32, kernel32.NewProc("GetTickCount64"), kernel32.NewProc("WindowsExporterMissingExport"))
+	require.Error(t, missingExport)
+
+	missingLibrary := lazyproc.Find(missingDLL, missingDLL.NewProc("A"), missingDLL.NewProc("B"))
+	require.Error(t, missingLibrary)
+
+	for name, tc := range map[string]struct {
+		err      error
+		expected bool
+	}{
+		"missing export": {
+			err:      fmt.Errorf("error build collector printer: %w", missingExport),
+			expected: true,
+		},
+		"missing DLL": {
+			err:      fmt.Errorf("error build collector dhcp: DHCP server API not available: %w", missingLibrary),
+			expected: true,
+		},
+		"joined bindings": {
+			err:      fmt.Errorf("error build collector gpu: GPU APIs not available: %w", errors.Join(missingExport, missingLibrary)),
+			expected: true,
+		},
+		"hyperv sub-collectors": {
+			err: fmt.Errorf("error build collector hyperv: %w", errors.Join(
+				fmt.Errorf("failed to build host collector: %w", missingLibrary),
+				fmt.Errorf("failed to build wmi_health collector: %w", missingExport),
+			)),
+			expected: true,
+		},
+		"hyperv sub-collectors with an unexpected failure": {
+			err: fmt.Errorf("error build collector hyperv: %w", errors.Join(
+				fmt.Errorf("failed to build host collector: %w", missingLibrary),
+				fmt.Errorf("failed to build datastore collector: %w", windows.ERROR_ACCESS_DENIED),
+			)),
+			expected: false,
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			require.Equal(t, tc.expected, expectedBuildError(tc.err), tc.err)
+		})
+	}
+}