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eiriktsarpalis merged 2 commits into from
Apr 15, 2022
Merged

Improve JsonTestHelpers.AssertJsonEqual error messages #67973

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339e78c
Make JsonTestHelpers.AssertJsonEqual print contextual error messages
eiriktsarpalis Apr 13, 2022
340d90a
address feedback
eiriktsarpalis Apr 15, 2022
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73 changes: 57 additions & 16 deletions src/libraries/System.Text.Json/tests/Common/JsonTestHelper.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text.Json.Serialization.Tests;
using System.Text.Json.Serialization.Tests.Schemas.OrderPayload;
using System.Text.RegularExpressions;
Expand All @@ -17,59 +18,99 @@ public static void AssertJsonEqual(string expected, string actual)
{
using JsonDocument expectedDom = JsonDocument.Parse(expected);
using JsonDocument actualDom = JsonDocument.Parse(actual);
AssertJsonEqual(expectedDom.RootElement, actualDom.RootElement);
AssertJsonEqual(expectedDom.RootElement, actualDom.RootElement, new());
}

private static void AssertJsonEqual(JsonElement expected, JsonElement actual)
private static void AssertJsonEqual(JsonElement expected, JsonElement actual, Stack<object> path)
{
JsonValueKind valueKind = expected.ValueKind;
Assert.Equal(valueKind, actual.ValueKind);
AssertTrue(passCondition: valueKind == actual.ValueKind);

switch (valueKind)
{
case JsonValueKind.Object:
var propertyNames = new HashSet<string>();

var expectedProperties = new List<string>();
foreach (JsonProperty property in expected.EnumerateObject())
{
propertyNames.Add(property.Name);
expectedProperties.Add(property.Name);
}

var actualProperties = new List<string>();
foreach (JsonProperty property in actual.EnumerateObject())
{
propertyNames.Add(property.Name);
actualProperties.Add(property.Name);
}

foreach (string name in propertyNames)
foreach (var property in expectedProperties.Except(actualProperties))
{
AssertJsonEqual(expected.GetProperty(name), actual.GetProperty(name));
AssertTrue(passCondition: false, $"Property \"{property}\" missing from actual object.");
}

foreach (var property in actualProperties.Except(expectedProperties))
{
AssertTrue(passCondition: false, $"Actual object defines additional property \"{property}\".");
}

foreach (string name in expectedProperties)
{
path.Push(name);
AssertJsonEqual(expected.GetProperty(name), actual.GetProperty(name), path);
path.Pop();
}
break;
case JsonValueKind.Array:
JsonElement.ArrayEnumerator expectedEnumerator = actual.EnumerateArray();
JsonElement.ArrayEnumerator actualEnumerator = expected.EnumerateArray();
JsonElement.ArrayEnumerator expectedEnumerator = expected.EnumerateArray();
JsonElement.ArrayEnumerator actualEnumerator = actual.EnumerateArray();

int i = 0;
while (expectedEnumerator.MoveNext())
{
Assert.True(actualEnumerator.MoveNext());
AssertJsonEqual(expectedEnumerator.Current, actualEnumerator.Current);
AssertTrue(passCondition: actualEnumerator.MoveNext(), "Actual array contains fewer elements.");
path.Push(i++);
AssertJsonEqual(expectedEnumerator.Current, actualEnumerator.Current, path);
path.Pop();
}

Assert.False(actualEnumerator.MoveNext());
AssertTrue(passCondition: !actualEnumerator.MoveNext(), "Actual array contains additional elements.");
break;
case JsonValueKind.String:
Assert.Equal(expected.GetString(), actual.GetString());
AssertTrue(passCondition: expected.GetString() == actual.GetString());
break;
case JsonValueKind.Number:
case JsonValueKind.True:
case JsonValueKind.False:
case JsonValueKind.Null:
Assert.Equal(expected.GetRawText(), actual.GetRawText());
AssertTrue(passCondition: expected.GetRawText() == actual.GetRawText());
break;
default:
Debug.Fail($"Unexpected JsonValueKind: JsonValueKind.{valueKind}.");
break;
}

void AssertTrue(bool passCondition, string? message = null)
{
if (!passCondition)
{
message ??= "Expected JSON does not match actual value";
Assert.Fail($"{message}\nExpected JSON: {expected}\n Actual JSON: {actual}\n in JsonPath: {BuildJsonPath(path)}");
}

// TODO replace with JsonPath implementation for JsonElement
// cf. https://github.com/dotnet/runtime/issues/31068
static string BuildJsonPath(Stack<object> path)
{
var sb = new StringBuilder("$");
foreach (object node in path.Reverse())
{
string pathNode = node is string propertyName
? "." + propertyName
: $"[{(int)node}]";

sb.Append(pathNode);
}
return sb.ToString();
}
}
}

public static async Task<List<T>> ToListAsync<T>(this IAsyncEnumerable<T> source)
Expand Down