Many unittests for internal folder

internal/filter/filter_test.go

@@ -0,0 +1,39 @@
+// This file is Free Software under the MIT License
+// without warranty, see README.md and LICENSES/MIT.txt for details.
+//
+// SPDX-License-Identifier: MIT
+//
+// SPDX-FileCopyrightText: 2023 German Federal Office for Information Security (BSI) <https://www.bsi.bund.de>
+// Software-Engineering: 2023 Intevation GmbH <https://intevation.de>
+
+// Package filter implements helps to filter advisories.
+package filter
+
+import (
+	"testing"
+)
+
+// NewPatternMatcher compiles a new list of regular expression from
+// a given list of strings.
+func TestNewPatternMatcher(t *testing.T) {
+	var regex []string 
+	if pm, err := NewPatternMatcher(regex); pm == nil || err != nil {
+		t.Errorf("Failure: Did not compile valid regex pattern")		
+	}
+	regex = append(regex, "++")
+	if pm, err := NewPatternMatcher(regex); pm != nil || err == nil {
+		t.Errorf("Failure: No error thrown at invalid compile pattern")		
+	}
+}
+
+// Matches returns true if the given string matches any of the expressions.
+func TestMatches(t *testing.T) {
+	regex :=  []string{"a"}  
+	pm, _ := NewPatternMatcher(regex)
+	if !pm.Matches("a") {
+		t.Errorf("Failure: Did not match two identical strings")
+	}
+	if pm.Matches("b") {
+		t.Errorf("Failure: Matched two non-matching strings")
+	}
+}