print error when glob doesn't match any files (#370)

internal/diff.go

@@ -139,13 +139,14 @@ func normalDiff(loader load.Loader, base, revision string, config *diff.Config)
 func composedDiff(loader load.Loader, base, revision string, config *diff.Config) (*diff.Diff, *diff.OperationsSourcesMap, *ReturnError) {
 	s1, err := load.FromGlob(loader, base)
 	if err != nil {
-		return nil, nil, getErrFailedToLoadSpec("base", base, err)
+		return nil, nil, getErrFailedToLoadSpecs("base", base, err)
 	}
 
 	s2, err := load.FromGlob(loader, revision)
 	if err != nil {
-		return nil, nil, getErrFailedToLoadSpec("revision", revision, err)
+		return nil, nil, getErrFailedToLoadSpecs("revision", revision, err)
 	}
+
 	diffReport, operationsSources, err := diff.GetPathsDiff(config, s1, s2)
 	if err != nil {
 		return nil, nil, getErrDiffFailed(err)

internal/errors.go

@@ -23,6 +23,13 @@ func getErrFailedToLoadSpec(what string, path string, err error) *ReturnError {
 	}
 }
 
+func getErrFailedToLoadSpecs(what string, path string, err error) *ReturnError {
+	return &ReturnError{
+		error: fmt.Errorf("failed to load %s specs from glob %q with %v", what, path, err),
+		Code:  103,
+	}
+}
+
 func getErrDiffFailed(err error) *ReturnError {
 	return &ReturnError{
 		error: fmt.Errorf("diff failed with %v", err),

internal/run_test.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"encoding/json"
 	"io"
-	"os"
 	"strings"
 	"testing"
 
@@ -63,7 +62,30 @@ func Test_Summary(t *testing.T) {
 }
 
 func Test_InvalidFile(t *testing.T) {
-	require.Equal(t, 102, internal.Run(cmdToArgs("oasdiff diff no-file ../data/openapi-test3.yaml"), os.Stdout, io.Discard))
+	var stderr bytes.Buffer
+	require.Equal(t, 102, internal.Run(cmdToArgs("oasdiff diff no-file ../data/openapi-test3.yaml"), io.Discard, &stderr))
+	require.Condition(t, func() (success bool) {
+		return stderr.String() == "Error: failed to load base spec from \"no-file\" with open no-file: no such file or directory\n" ||
+			stderr.String() == "Error: failed to load base spec from \"no-file\" with open no-file: The system cannot find the file specified.\n" // windows
+	})
+}
+
+func Test_InvalidGlob(t *testing.T) {
+	var stderr bytes.Buffer
+	require.Equal(t, 103, internal.Run(cmdToArgs(`oasdiff diff -c "a[" ../data/openapi-test3.yaml`), io.Discard, &stderr))
+	require.Equal(t, "Error: failed to load base specs from glob \"\\\"a[\\\"\" with syntax error in pattern\n", stderr.String())
+}
+
+func Test_GlobNoFiles(t *testing.T) {
+	var stderr bytes.Buffer
+	require.Equal(t, 103, internal.Run(cmdToArgs("oasdiff diff -c no-file ../data/openapi-test3.yaml"), io.Discard, &stderr))
+	require.Equal(t, "Error: failed to load base specs from glob \"no-file\" with no matching files\n", stderr.String())
+}
+
+func Test_GlobWithUrl(t *testing.T) {
+	var stderr bytes.Buffer
+	require.Equal(t, 103, internal.Run(cmdToArgs("oasdiff diff -c ../data/openapi-test1.yaml https://"), io.Discard, &stderr))
+	require.Equal(t, "Error: failed to load revision specs from glob \"https://\" with no matching files (should be a glob, not a URL)\n", stderr.String())
 }
 
 func Test_DiffInvalidFormat(t *testing.T) {

load/spec_info.go

@@ -1,6 +1,9 @@
 package load
 
 import (
+	"errors"
+	"net/url"
+
 	"github.com/getkin/kin-openapi/openapi3"
 	"github.com/yargevad/filepathx"
 )
@@ -37,5 +40,19 @@ func FromGlob(loader Loader, glob string) ([]SpecInfo, error) {
 		result = append(result, SpecInfo{Url: file, Spec: spec})
 	}
 
-	return result, nil
+	if len(result) > 0 {
+		return result, nil
+	}
+
+	if isUrl(glob) {
+		return nil, errors.New("no matching files (should be a glob, not a URL)")
+	}
+
+	return nil, errors.New("no matching files")
+
+}
+
+func isUrl(spec string) bool {
+	_, err := url.ParseRequestURI(spec)
+	return err == nil
 }