Add tests for CLI flags

This includes various bug fixes, especially around the area of missing
names for `<kind>/<name>` formats.

Signed-off-by: Hidde Beydals <hello@hidde.co>

internal/flags/kustomization_source_test.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2020 The Flux 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.
+*/
+
+package flags
+
+import (
+	"fmt"
+	"testing"
+
+	sourcev1 "github.com/fluxcd/source-controller/api/v1beta1"
+)
+
+func TestKustomizationSource_Set(t *testing.T) {
+	tests := []struct {
+		name      string
+		str       string
+		expect    string
+		expectErr bool
+	}{
+		{"supported", fmt.Sprintf("%s/foo", sourcev1.GitRepositoryKind), fmt.Sprintf("%s/foo", sourcev1.GitRepositoryKind), false},
+		{"default kind", "foo", fmt.Sprintf("%s/foo", sourcev1.GitRepositoryKind), false},
+		{"unsupported", "Unsupported/kind", "", true},
+		{"missing name", fmt.Sprintf("%s/", sourcev1.GitRepositoryKind), "", true},
+		{"empty", "", "", true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var s KustomizationSource
+			if err := s.Set(tt.str); (err != nil) != tt.expectErr {
+				t.Errorf("Set() error = %v, expectErr %v", err, tt.expectErr)
+			}
+			if str := s.String(); str != tt.expect {
+				t.Errorf("Set() = %v, expect %v", str, tt.expect)
+			}
+		})
+	}
+}