Harden MapQuest exception handling

Root cause: MapQuest transport errors still exposed key-bearing request URLs in exception context and used raw Exception instead of provider-specific exceptions.

Author: niemyjski

src/Geocoding.MapQuest/MapQuestGeocoder.cs

@@ -212,7 +212,7 @@ private HttpRequestMessage CreateRequest(BaseRequest f)
 
     private async Task<MapQuestResponse> Parse(HttpClient client, HttpRequestMessage request, CancellationToken cancellationToken)
     {
-        string requestInfo = $"[{request.Method}] {request.RequestUri}";
+        string requestInfo = BuildRequestInfo(request);
         try
         {
             using var response = await client.SendAsync(request, cancellationToken).ConfigureAwait(false);
@@ -221,21 +221,32 @@ private async Task<MapQuestResponse> Parse(HttpClient client, HttpRequestMessage
             var json = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
 
             if (!response.IsSuccessStatusCode)
-                throw new Exception($"{(int)response.StatusCode} {requestInfo} | {response.ReasonPhrase}{BuildResponsePreview(json)}");
+                throw new MapQuestGeocodingException($"{(int)response.StatusCode} {requestInfo} | {response.ReasonPhrase}{BuildResponsePreview(json)}");
 
             if (String.IsNullOrWhiteSpace(json))
-                throw new Exception("Remote system response with blank: " + requestInfo);
+                throw new MapQuestGeocodingException("Remote system response with blank: " + requestInfo);
 
             MapQuestResponse? o = json.FromJson<MapQuestResponse>();
             if (o is null)
-                throw new Exception("Unable to deserialize remote response: " + requestInfo);
+                throw new MapQuestGeocodingException("Unable to deserialize remote response: " + requestInfo);
 
             return o;
         }
         catch (HttpRequestException ex)
         {
-            throw new Exception($"{requestInfo} | {ex.Message}", ex);
+            throw new MapQuestGeocodingException($"{requestInfo} | {ex.Message}", ex);
         }
+        catch (Exception ex) when (ex is not MapQuestGeocodingException)
+        {
+            throw new MapQuestGeocodingException(ex);
+        }
+    }
+
+    private static string BuildRequestInfo(HttpRequestMessage request)
+    {
+        string method = request.Method.Method;
+        string requestUri = request.RequestUri?.GetLeftPart(UriPartial.Path) ?? "(unknown-uri)";
+        return $"[{method}] {requestUri}";
     }
 
     private static string BuildResponsePreview(string? body)

src/Geocoding.MapQuest/MapQuestGeocodingException.cs

@@ -0,0 +1,33 @@
+using Geocoding.Core;
+
+namespace Geocoding.MapQuest;
+
+/// <summary>
+/// Represents an error returned by the MapQuest geocoding provider.
+/// </summary>
+public class MapQuestGeocodingException : GeocodingException
+{
+    private const string DefaultMessage = "There was an error processing the geocoding request. See InnerException for more information.";
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MapQuestGeocodingException"/> class.
+    /// </summary>
+    /// <param name="innerException">The underlying provider exception.</param>
+    public MapQuestGeocodingException(Exception innerException)
+        : base(DefaultMessage, innerException) { }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MapQuestGeocodingException"/> class.
+    /// </summary>
+    /// <param name="message">The provider error message.</param>
+    public MapQuestGeocodingException(string message)
+        : base(message) { }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MapQuestGeocodingException"/> class.
+    /// </summary>
+    /// <param name="message">The provider error message.</param>
+    /// <param name="innerException">The underlying provider exception.</param>
+    public MapQuestGeocodingException(string message, Exception innerException)
+        : base(message, innerException) { }
+}

test/Geocoding.Tests/MapQuestGeocoderTest.cs

@@ -128,11 +128,12 @@ public async Task Geocode_ConnectionFailure_IncludesRequestContext()
         var geocoder = new TestableMapQuestGeocoder(new TestHttpMessageHandler((_, _) => throw new HttpRequestException("Name or service not known")));
 
         // Act
-        var exception = await Assert.ThrowsAsync<Exception>(() => geocoder.GeocodeAsync("1600 pennsylvania ave nw, washington dc", TestContext.Current.CancellationToken));
+        var exception = await Assert.ThrowsAsync<MapQuestGeocodingException>(() => geocoder.GeocodeAsync("1600 pennsylvania ave nw, washington dc", TestContext.Current.CancellationToken));
 
         // Assert
         Assert.Contains("[POST]", exception.Message, StringComparison.Ordinal);
         Assert.Contains("mapquestapi.com/geocoding/v1/address", exception.Message, StringComparison.Ordinal);
+        Assert.DoesNotContain("key=mapquest-key", exception.Message, StringComparison.Ordinal);
         Assert.IsType<HttpRequestException>(exception.InnerException);
     }
 
@@ -144,11 +145,12 @@ public async Task Geocode_StatusFailure_UsesTrimmedPreviewMessage()
         var geocoder = new TestableMapQuestGeocoder(new TestHttpMessageHandler((_, _) => TestHttpMessageHandler.CreateResponseAsync(HttpStatusCode.BadGateway, "Bad Gateway", body)));
 
         // Act
-        var exception = await Assert.ThrowsAsync<Exception>(() => geocoder.GeocodeAsync("1600 pennsylvania ave nw, washington dc", TestContext.Current.CancellationToken));
+        var exception = await Assert.ThrowsAsync<MapQuestGeocodingException>(() => geocoder.GeocodeAsync("1600 pennsylvania ave nw, washington dc", TestContext.Current.CancellationToken));
 
         // Assert
         Assert.Contains("502", exception.Message, StringComparison.Ordinal);
         Assert.Contains("Response preview:", exception.Message, StringComparison.Ordinal);
+        Assert.DoesNotContain("key=mapquest-key", exception.Message, StringComparison.Ordinal);
         Assert.DoesNotContain(body, exception.Message, StringComparison.Ordinal);
     }