Add flux version command

Signed-off-by: Somtochi Onyekwere <somtochionyekwere@gmail.com>

cmd/flux/version_utils_test.go

@@ -0,0 +1,55 @@
+// +build unit
+
+/*
+Copyright 2021 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 main
+
+import (
+	"testing"
+)
+
+func TestVersion(t *testing.T) {
+	cmd := cmdTestCase{
+		args:   "--version",
+		assert: assertGoldenValue("flux version 0.0.0-dev.0\n"),
+	}
+	cmd.runTestCmd(t)
+}
+
+func TestVersionCmd(t *testing.T) {
+	tests := []struct {
+		args     string
+		expected string
+	}{
+		{
+			args:     "version --client",
+			expected: "flux: v0.0.0-dev.0\n",
+		},
+		{
+			args:     "version --client -o json",
+			expected: "{\n  \"flux\": \"v0.0.0-dev.0\"\n}\n",
+		},
+	}
+
+	for _, tt := range tests {
+		cmd := cmdTestCase{
+			args:   tt.args,
+			assert: assertGoldenValue(tt.expected),
+		}
+		cmd.runTestCmd(t)
+	}
+}