Add tests (#2)

* Initial tests draft.

* Add tests for parsing jwt token

* Further code optimisations

cache_test.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+func (suite *Tests) Test_cacheLookup() {
+	type args struct {
+		hash string
+	}
+	tests := []struct {
+		name     string
+		args     args
+		want     []byte
+		addCache struct {
+			data []byte
+		}
+	}{
+		{
+			name: "test_non_existent",
+			args: args{
+				hash: "00000000000000000000000000000000000000",
+			},
+			want: nil,
+		},
+		{
+			name: "test_existent",
+			args: args{
+				hash: "00000000000000000000000000000000000001",
+			},
+			want: []byte("it's fine."),
+			addCache: struct {
+				data []byte
+			}{
+				data: []byte("it's fine."),
+			},
+		},
+	}
+	for _, tt := range tests {
+		suite.T().Run(tt.name, func(t *testing.T) {
+			if tt.addCache.data != nil {
+				cfg.Cache.CacheClient.Set(tt.args.hash, tt.addCache.data, time.Duration(1)*time.Second)
+			}
+			got := cacheLookup(tt.args.hash)
+			assert.Equal(tt.want, got, "Unexpected cache lookup result")
+		})
+	}
+}