Fix faulty shell file handling

Parsing errors are meant to be discarded but aren't. This patch
changes the code so that the error is indeed discarded and checking
continues as intended and adds a unit test for it.

Signed-off-by: Arnaud J Le Hors <[email protected]>

checks/shell_download_validate.go

@@ -914,6 +914,7 @@ func validateShellFile(pathfn string, content []byte, dl checker.DetailLogger) (
 	if err != nil && errors.Is(err, sce.ErrorShellParsing) {
 		// Discard and print this particular error for now.
 		dl.Debug(err.Error())
+		err = nil
 	}
 	return r, err
 }

checks/shell_download_validate_test.go

@@ -17,6 +17,8 @@ package checks
 import (
 	"os"
 	"testing"
+
+	scut "github.com/ossf/scorecard/v3/utests"
 )
 
 func TestIsSupportedShellScriptFile(t *testing.T) {
@@ -86,3 +88,20 @@ func TestIsSupportedShellScriptFile(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateShellFile(t *testing.T) {
+	t.Parallel()
+	filename := "testdata/script-invalid.sh"
+	var content []byte
+	var err error
+
+	content, err = os.ReadFile(filename)
+	if err != nil {
+		t.Errorf("cannot read file: %v", err)
+	}
+	dl := scut.TestDetailLogger{}
+	_, err = validateShellFile(filename, content, &dl)
+	if err != nil {
+		t.Errorf("failed to discard shell parsing error: %v", err)
+	}
+}

checks/testdata/script-invalid.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+# Copyright 2021 Security Scorecard 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.
+
+# syntax error: unexpected token 'fi'
+fi