feat: Client secret from env var

Fauna.Test/Configuration.Tests.cs

@@ -16,6 +16,30 @@ public void ConstructorWorksFine()
         Assert.IsTrue(b.DisposeHttpClient);
     }
 
+    [Test]
+    public void ConstructorUsesEnvVar()
+    {
+        Environment.SetEnvironmentVariable("FAUNA_SECRET", "secret");
+        var b = new Configuration();
+
+        Assert.AreEqual("secret", b.Secret);
+        Assert.AreEqual(Endpoints.Default, b.Endpoint);
+        Assert.IsTrue(b.DisposeHttpClient);
+    }
+
+    [Test]
+    public void ConstructorThrowsWithNullSecret()
+    {
+        string? currentVal = Environment.GetEnvironmentVariable("FAUNA_SECRET");
+        Assert.Throws<ArgumentNullException>(() =>
+        {
+            Environment.SetEnvironmentVariable("FAUNA_SECRET", null);
+            var b = new Configuration();
+
+        });
+        Environment.SetEnvironmentVariable("FAUNA_SECRET", currentVal);
+    }
+
     [Test]
     public void ConstructorWithHttpClient()
     {

Fauna/Client.cs

@@ -37,6 +37,12 @@ public class Client : BaseClient, IDisposable
     /// </summary>
     public long LastSeenTxn { get; private set; }
 
+    /// <summary>
+    /// Initializes a new instance of a Client with the default configuration.
+    /// Assumes the environment variable FAUNA_SECRET is set.
+    /// </summary>
+    public Client() : this(new Configuration()) { }
+
     /// <summary>
     /// Initializes a new instance of a Client with a secret.
     /// </summary>

Fauna/Configuration.cs

@@ -11,17 +11,17 @@ public record class Configuration
     /// <summary>
     /// Whether the <see cref="Client"/> should dispose of the  <see cref="HttpClient"/> on Dispose.
     /// </summary>
-    public bool DisposeHttpClient { get; }
+    public bool DisposeHttpClient { get; } = true;
 
     /// <summary>
     /// The HTTP Client to use for requests.
     /// </summary>
-    public HttpClient HttpClient { get; }
+    public HttpClient HttpClient { get; } = new HttpClient { Timeout = TimeSpan.FromSeconds(5) };
 
     /// <summary>
     /// The secret key used for authentication.
     /// </summary>
-    public string Secret { get; init; }
+    public string Secret { get; init; } = Environment.GetEnvironmentVariable("FAUNA_SECRET") ?? string.Empty;
 
     /// <summary>
     /// The endpoint URL of the Fauna server.
@@ -44,26 +44,28 @@ public record class Configuration
     /// </summary>
     public IStatsCollector? StatsCollector { get; init; } = new StatsCollector();
 
+    public Configuration()
+    {
+        if (string.IsNullOrEmpty(Secret))
+        {
+            throw new ArgumentNullException(nameof(Secret), "Need to set FAUNA_SECRET environment variable or pass a secret as a parameter when creating the Client.");
+        }
+    }
+
     /// <summary>
     /// Initializes a new instance of the <see cref="Configuration"/> record with the specified secret key.
     /// </summary>
     /// <param name="secret">The secret key used for authentication.</param>
     /// <param name="httpClient">The <see cref="HttpClient"/> to use.</param>
     public Configuration(string secret, HttpClient? httpClient = null)
     {
+        Secret = secret;
         if (httpClient is null)
         {
-            HttpClient = new HttpClient
-            {
-                Timeout = TimeSpan.FromSeconds(5)
-            };
-            DisposeHttpClient = true;
-        }
-        else
-        {
-            HttpClient = httpClient;
+            return;
         }
 
-        Secret = secret;
+        HttpClient = httpClient;
+        DisposeHttpClient = false;
     }
 }