Add tests for clusterinfo collector (prometheus-community#792)

* Add tests for clusterinfo collector

Signed-off-by: Joe Adams <github@joeadams.io>

* Add license header

Signed-off-by: Joe Adams <github@joeadams.io>

---------

Signed-off-by: Joe Adams <github@joeadams.io>

collector/cluster_info_test.go

@@ -0,0 +1,93 @@
+// Copyright 2023 The Prometheus 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 collector
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/go-kit/log"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+func TestClusterInfo(t *testing.T) {
+	// Testcases created using:
+	//  docker run -p 9200:9200 -e "discovery.type=single-node" elasticsearch:${VERSION}
+	//  curl http://localhost:9200/ > fixtures/cluster_info/${VERSION}.json
+
+	tests := []struct {
+		name string
+		file string
+		want string
+	}{
+		{
+			name: "2.4.5",
+			file: "../fixtures/clusterinfo/2.4.5.json",
+			want: `# HELP elasticsearch_version Elasticsearch version information.
+            # TYPE elasticsearch_version gauge
+            elasticsearch_version{build_date="",build_hash="c849dd13904f53e63e88efc33b2ceeda0b6a1276",cluster="elasticsearch",cluster_uuid="3qps7bcWTqyzV49ApmPVfw",lucene_version="5.5.4",version="2.4.5"} 1
+      `,
+		},
+		{
+			name: "5.4.2",
+			file: "../fixtures/clusterinfo/5.4.2.json",
+			want: `# HELP elasticsearch_version Elasticsearch version information.
+            # TYPE elasticsearch_version gauge
+            elasticsearch_version{build_date="2017-06-15T02:29:28.122Z",build_hash="929b078",cluster="elasticsearch",cluster_uuid="kbqi7yhQT-WlPdGL2m0xJg",lucene_version="6.5.1",version="5.4.2"} 1
+      `,
+		},
+		{
+			name: "7.13.1",
+			file: "../fixtures/clusterinfo/7.13.1.json",
+			want: `# HELP elasticsearch_version Elasticsearch version information.
+            # TYPE elasticsearch_version gauge
+            elasticsearch_version{build_date="2021-05-28T17:40:59.346932922Z",build_hash="9a7758028e4ea59bcab41c12004603c5a7dd84a9",cluster="docker-cluster",cluster_uuid="aCMrCY1VQpqJ6U4Sw_xdiw",lucene_version="8.8.2",version="7.13.1"} 1
+      `,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f, err := os.Open(tt.file)
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer f.Close()
+
+			ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				io.Copy(w, f)
+			}))
+			defer ts.Close()
+
+			u, err := url.Parse(ts.URL)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			c, err := NewClusterInfo(log.NewNopLogger(), u, http.DefaultClient)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if err := testutil.CollectAndCompare(wrapCollector{c}, strings.NewReader(tt.want)); err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}

fixtures/clusterinfo/2.4.5.json

@@ -0,0 +1,13 @@
+{
+  "name" : "Mys-Tech",
+  "cluster_name" : "elasticsearch",
+  "cluster_uuid" : "3qps7bcWTqyzV49ApmPVfw",
+  "version" : {
+    "number" : "2.4.5",
+    "build_hash" : "c849dd13904f53e63e88efc33b2ceeda0b6a1276",
+    "build_timestamp" : "2017-04-24T16:18:17Z",
+    "build_snapshot" : false,
+    "lucene_version" : "5.5.4"
+  },
+  "tagline" : "You Know, for Search"
+}

fixtures/clusterinfo/5.4.2.json

@@ -0,0 +1,13 @@
+{
+  "name" : "gOHPUga",
+  "cluster_name" : "elasticsearch",
+  "cluster_uuid" : "kbqi7yhQT-WlPdGL2m0xJg",
+  "version" : {
+    "number" : "5.4.2",
+    "build_hash" : "929b078",
+    "build_date" : "2017-06-15T02:29:28.122Z",
+    "build_snapshot" : false,
+    "lucene_version" : "6.5.1"
+  },
+  "tagline" : "You Know, for Search"
+}

fixtures/clusterinfo/7.13.1.json

@@ -0,0 +1,17 @@
+{
+  "name" : "e0630cfd8e1e",
+  "cluster_name" : "docker-cluster",
+  "cluster_uuid" : "aCMrCY1VQpqJ6U4Sw_xdiw",
+  "version" : {
+    "number" : "7.13.1",
+    "build_flavor" : "default",
+    "build_type" : "docker",
+    "build_hash" : "9a7758028e4ea59bcab41c12004603c5a7dd84a9",
+    "build_date" : "2021-05-28T17:40:59.346932922Z",
+    "build_snapshot" : false,
+    "lucene_version" : "8.8.2",
+    "minimum_wire_compatibility_version" : "6.8.0",
+    "minimum_index_compatibility_version" : "6.0.0-beta1"
+  },
+  "tagline" : "You Know, for Search"
+}