fail if no files found matching include directive

cmd/configure/main.go

@@ -81,6 +81,11 @@ func getIncludedConfs(confText string, confDir string) ([]string, error) {
 			if err != nil {
 				return nil, fmt.Errorf("failed to get 'include' files for %s: %w", conf, err)
 			}
+
+			if len(matchFiles) == 0 {
+				return nil, fmt.Errorf("failed to get 'include' files for %s: no matching files exist", conf)
+			}
+
 			includeFiles = append(includeFiles, matchFiles...)
 		}
 	}

cmd/configure/main_test.go

@@ -289,6 +289,21 @@ http {
 					Expect(buffer.String()).To(ContainSubstring(`/\/\/.conf: syntax error in pattern`))
 				})
 			})
+			context("when an include file does not exist", func() {
+				it.Before(func() {
+					Expect(ioutil.WriteFile(filepath.Join(workingDir, "nginx.conf"), []byte("include donotexist.conf;"), 0644)).To(Succeed())
+					command = exec.Command(path, filepath.Join(workingDir, "nginx.conf"), localModulePath, globalModulePath)
+					buffer = bytes.NewBuffer(nil)
+				})
+
+				it("exits non-zero", func() {
+					session, err := gexec.Start(command, buffer, buffer)
+					Expect(err).ToNot(HaveOccurred())
+					Eventually(session).Should(gexec.Exit(1), buffer.String)
+					Expect(buffer.String()).To(ContainSubstring(`failed to get 'include' files for /tmp/working-dir`))
+					Expect(buffer.String()).To(ContainSubstring("no matching files exist"))
+				})
+			})
 		})
 	}, spec.Report(report.Terminal{}))
 }