/
CallerIdentifier.cs
148 lines (120 loc) · 4.39 KB
/
CallerIdentifier.cs
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using System;
using System.Diagnostics;
using System.IO;
using System.Text.RegularExpressions;
using FluentAssertions.Common;
namespace FluentAssertions
{
/// <summary>
/// Tries to extract the name of the variable or invocation on which the assertion is executed.
/// </summary>
public static class CallerIdentifier
{
public static Action<string> logger = str => { };
#if NET45 || NET47 || NETSTANDARD2_0 || NETCOREAPP2_0
public static string DetermineCallerIdentity()
{
string caller = null;
StackTrace stack = new StackTrace(true);
foreach (StackFrame frame in stack.GetFrames())
{
logger(frame.ToString());
if (!IsDynamic(frame) && !IsDotNet(frame) && !IsCurrentAssembly(frame) && !IsCustomAssertion(frame))
{
caller = ExtractVariableNameFrom(frame) ?? caller;
break;
}
}
return caller;
}
private static bool IsCustomAssertion(StackFrame frame)
{
return frame.GetMethod().HasAttribute<CustomAssertionAttribute>();
}
private static bool IsDynamic(StackFrame frame)
{
return frame.GetMethod().DeclaringType == null;
}
private static bool IsCurrentAssembly(StackFrame frame)
{
return frame.GetMethod().DeclaringType.Assembly == typeof(CallerIdentifier).Assembly;
}
private static bool IsDotNet(StackFrame frame)
{
return frame.GetMethod().DeclaringType.Namespace
?.StartsWith("system", StringComparison.InvariantCultureIgnoreCase) == true;
}
private static string ExtractVariableNameFrom(StackFrame frame)
{
string caller = null;
int column = frame.GetFileColumnNumber();
string line = GetSourceCodeLineFrom(frame);
if ((line != null) && (column != 0) && (line.Length > 0))
{
string statement = line.Substring(Math.Min(column - 1, line.Length - 1));
logger(statement);
int indexOfShould = statement.IndexOf("Should", StringComparison.InvariantCulture);
if (indexOfShould != -1)
{
string candidate = statement.Substring(0, indexOfShould - 1);
logger(candidate);
if (!IsBooleanLiteral(candidate) && !IsNumeric(candidate) && !IsStringLiteral(candidate) &&
!UsesNewKeyword(candidate))
{
caller = candidate;
}
}
}
return caller;
}
private static string GetSourceCodeLineFrom(StackFrame frame)
{
string fileName = frame.GetFileName();
int expectedLineNumber = frame.GetFileLineNumber();
if (string.IsNullOrEmpty(fileName) || (expectedLineNumber == 0))
{
return null;
}
try
{
using (StreamReader reader = new StreamReader(File.OpenRead(fileName)))
{
string line;
int currentLine = 1;
while ((line = reader.ReadLine()) != null && currentLine < expectedLineNumber)
{
currentLine++;
}
return (currentLine == expectedLineNumber) ? line : null;
}
}
catch
{
// We don't care. Just assume the symbol file is not available or unreadable
return null;
}
}
private static bool UsesNewKeyword(string candidate)
{
return Regex.IsMatch(candidate, @"new(\s?\[|\s?\{|\s\w+)");
}
private static bool IsStringLiteral(string candidate)
{
return candidate.StartsWith("\"");
}
private static bool IsNumeric(string candidate)
{
return double.TryParse(candidate, out _);
}
private static bool IsBooleanLiteral(string candidate)
{
return candidate == "true" || candidate == "false";
}
#else
public static string DetermineCallerIdentity()
{
return null;
}
#endif
}
}