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Allow IEqualityComparer in string (Not)BeEquivalentTo assertion #2372

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Allow IEqualityComparer in string (Not)BeEquivalentTo assertion #2372

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6d51da8
Add overload for `StringAssertions.BeEquivalentTo` that accepts a `IE…
vbreuss Oct 9, 2023
69b68da
Update `releases.md`
vbreuss Oct 9, 2023
ffe311d
Rename tests
vbreuss Oct 14, 2023
a123e1d
Adjust StringStartStrategy to also use the `IEqualityComparer<string`
vbreuss Oct 14, 2023
8835fb7
Adjust Tests according to review from @IT-VBFK
vbreuss Oct 14, 2023
18c69cc
Add overload for `NotBeEquivalentTo`
vbreuss Oct 14, 2023
f6223e7
Also mention `NotBeEquivalentTo` in "releases.md"
vbreuss Oct 14, 2023
2cb8f57
Merge from latest `develop`
vbreuss Oct 20, 2023
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14 changes: 4 additions & 10 deletions Src/FluentAssertions/Common/StringExtensions.cs
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@@ -1,4 +1,5 @@
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using FluentAssertions.Formatting;
Expand All @@ -9,15 +10,13 @@ internal static class StringExtensions
{
/// <summary>
/// Finds the first index at which the <paramref name="value"/> does not match the <paramref name="expected"/>
/// string anymore, accounting for the specified <paramref name="stringComparison"/>.
/// string anymore, accounting for the specified <paramref name="comparer"/>.
/// </summary>
public static int IndexOfFirstMismatch(this string value, string expected, StringComparison stringComparison)
public static int IndexOfFirstMismatch(this string value, string expected, IEqualityComparer<string> comparer)
{
Func<char, char, bool> comparer = GetCharComparer(stringComparison);

for (int index = 0; index < value.Length; index++)
{
if (index >= expected.Length || !comparer(value[index], expected[index]))
if (index >= expected.Length || !comparer.Equals(value[index..(index + 1)], expected[index..(index + 1)]))
{
return index;
}
Expand All @@ -26,11 +25,6 @@ public static int IndexOfFirstMismatch(this string value, string expected, Strin
return -1;
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}

private static Func<char, char, bool> GetCharComparer(StringComparison stringComparison) =>
stringComparison == StringComparison.Ordinal
? (x, y) => x == y
: (x, y) => char.ToUpperInvariant(x) == char.ToUpperInvariant(y);

/// <summary>
/// Gets the quoted three characters at the specified index of a string, including the index itself.
/// </summary>
Expand Down
81 changes: 73 additions & 8 deletions Src/FluentAssertions/Primitives/StringAssertions.cs
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Expand Up @@ -54,7 +54,7 @@ public StringAssertions(string value)
public AndConstraint<TAssertions> Be(string expected, string because = "", params object[] becauseArgs)
{
var stringEqualityValidator = new StringValidator(
new StringEqualityStrategy(StringComparison.Ordinal),
new StringEqualityStrategy(StringComparer.Ordinal),
because, becauseArgs);

stringEqualityValidator.Validate(Subject, expected);
Expand Down Expand Up @@ -110,11 +110,40 @@ public AndConstraint<TAssertions> BeOneOf(IEnumerable<string> validValues, strin
/// <param name="becauseArgs">
/// Zero or more objects to format using the placeholders in <paramref name="because" />.
/// </param>
public AndConstraint<TAssertions> BeEquivalentTo(string expected, string because = "",
params object[] becauseArgs)
public AndConstraint<TAssertions> BeEquivalentTo(string expected,
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string because = "", params object[] becauseArgs)
{
var expectation = new StringValidator(
new StringEqualityStrategy(StringComparison.OrdinalIgnoreCase),
new StringEqualityStrategy(StringComparer.OrdinalIgnoreCase),
because, becauseArgs);

expectation.Validate(Subject, expected);

return new AndConstraint<TAssertions>((TAssertions)this);
}

/// <summary>
/// Asserts that a string is exactly the same as another string, using the provided <paramref name="comparer"/>.
/// </summary>
/// <param name="expected">
/// The string that the subject is expected to be equivalent to.
/// </param>
/// <param name="comparer">
/// The string equality comparer.
/// </param>
/// <param name="because">
/// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
/// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
/// </param>
/// <param name="becauseArgs">
/// Zero or more objects to format using the placeholders in <paramref name="because" />.
/// </param>
public AndConstraint<TAssertions> BeEquivalentTo(string expected,
IEqualityComparer<string> comparer,
string because = "", params object[] becauseArgs)
{
var expectation = new StringValidator(
new StringEqualityStrategy(comparer),
because, becauseArgs);

expectation.Validate(Subject, expected);
Expand All @@ -136,8 +165,8 @@ public AndConstraint<TAssertions> BeOneOf(IEnumerable<string> validValues, strin
/// <param name="becauseArgs">
/// Zero or more objects to format using the placeholders in <paramref name="because" />.
/// </param>
public AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected, string because = "",
params object[] becauseArgs)
public AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected,
string because = "", params object[] becauseArgs)
{
bool notEquivalent;

Expand All @@ -155,6 +184,42 @@ public AndConstraint<TAssertions> BeOneOf(IEnumerable<string> validValues, strin
return new AndConstraint<TAssertions>((TAssertions)this);
}

/// <summary>
/// Asserts that a string is not exactly the same as another string, using the provided <paramref name="comparer"/>.
/// </summary>
/// <param name="unexpected">
/// The string that the subject is not expected to be equivalent to.
/// </param>
/// <param name="comparer">
/// The string equality comparer.
/// </param>
/// <param name="because">
/// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
/// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
/// </param>
/// <param name="becauseArgs">
/// Zero or more objects to format using the placeholders in <paramref name="because" />.
/// </param>
public AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected,
IEqualityComparer<string> comparer,
string because = "", params object[] becauseArgs)
{
bool notEquivalent;

using (var scope = new AssertionScope())
{
Subject.Should().BeEquivalentTo(unexpected, comparer);
notEquivalent = scope.Discard().Length > 0;
}

Execute.Assertion
.ForCondition(notEquivalent)
.BecauseOf(because, becauseArgs)
.FailWith("Expected {context:string} not to be equivalent to {0}{reason}, but they are.", unexpected);

return new AndConstraint<TAssertions>((TAssertions)this);
}

/// <summary>
/// Asserts that a string is not exactly the same as the specified <paramref name="unexpected"/>,
/// including the casing and any leading or trailing whitespace.
Expand Down Expand Up @@ -675,7 +740,7 @@ public AndConstraint<TAssertions> StartWith(string expected, string because = ""
Guard.ThrowIfArgumentIsNull(expected, nameof(expected), "Cannot compare start of string with <null>.");

var stringStartValidator = new StringValidator(
new StringStartStrategy(StringComparison.Ordinal),
new StringStartStrategy(StringComparer.Ordinal),
because, becauseArgs);

stringStartValidator.Validate(Subject, expected);
Expand Down Expand Up @@ -728,7 +793,7 @@ public AndConstraint<TAssertions> NotStartWith(string unexpected, string because
Guard.ThrowIfArgumentIsNull(expected, nameof(expected), "Cannot compare string start equivalence with <null>.");

var stringStartValidator = new StringValidator(
new StringStartStrategy(StringComparison.OrdinalIgnoreCase),
new StringStartStrategy(StringComparer.OrdinalIgnoreCase),
because, becauseArgs);

stringStartValidator.Validate(Subject, expected);
Expand Down
24 changes: 12 additions & 12 deletions Src/FluentAssertions/Primitives/StringEqualityStrategy.cs
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@@ -1,4 +1,5 @@
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using FluentAssertions.Common;
Expand All @@ -8,11 +9,13 @@ namespace FluentAssertions.Primitives;

internal class StringEqualityStrategy : IStringComparisonStrategy
{
private readonly StringComparison comparisonMode;
private readonly IEqualityComparer<string> comparer;
private readonly bool ignoringCase;

public StringEqualityStrategy(StringComparison comparisonMode)
public StringEqualityStrategy(IEqualityComparer<string> comparer)
{
this.comparisonMode = comparisonMode;
this.comparer = comparer;
ignoringCase = comparer.Equals("A", "a");
}

public void ValidateAgainstMismatch(IAssertionScope assertion, string subject, string expected)
Expand All @@ -21,7 +24,7 @@ public void ValidateAgainstMismatch(IAssertionScope assertion, string subject, s

if (expected.IsLongOrMultiline() || subject.IsLongOrMultiline())
{
int indexOfMismatch = subject.IndexOfFirstMismatch(expected, comparisonMode);
int indexOfMismatch = subject.IndexOfFirstMismatch(expected, comparer);

if (indexOfMismatch == -1)
{
Expand All @@ -47,7 +50,7 @@ public void ValidateAgainstMismatch(IAssertionScope assertion, string subject, s
}
else if (ValidateAgainstLengthDifferences(assertion, subject, expected))
{
int indexOfMismatch = subject.IndexOfFirstMismatch(expected, comparisonMode);
int indexOfMismatch = subject.IndexOfFirstMismatch(expected, comparer);

if (indexOfMismatch != -1)
{
Expand All @@ -63,21 +66,18 @@ public string ExpectationDescription
{
get
{
string predicateDescription = IgnoreCase ? "be equivalent to" : "be";
string predicateDescription = ignoringCase ? "be equivalent to" : "be";
return "Expected {context:string} to " + predicateDescription + " ";
}
}

private bool IgnoreCase
=> comparisonMode == StringComparison.OrdinalIgnoreCase;

private void ValidateAgainstSuperfluousWhitespace(IAssertionScope assertion, string subject, string expected)
{
assertion
.ForCondition(!(expected.Length > subject.Length && expected.TrimEnd().Equals(subject, comparisonMode)))
.ForCondition(!(expected.Length > subject.Length && comparer.Equals(expected.TrimEnd(), subject)))
.FailWith(ExpectationDescription + "{0}{reason}, but it misses some extra whitespace at the end.", expected)
.Then
.ForCondition(!(subject.Length > expected.Length && subject.TrimEnd().Equals(expected, comparisonMode)))
.ForCondition(!(subject.Length > expected.Length && comparer.Equals(subject.TrimEnd(), expected)))
.FailWith(ExpectationDescription + "{0}{reason}, but it has unexpected whitespace at the end.", expected);
}

Expand All @@ -98,7 +98,7 @@ private bool ValidateAgainstLengthDifferences(IAssertionScope assertion, string

private string GetMismatchSegmentForStringsOfDifferentLengths(string subject, string expected)
{
int indexOfMismatch = subject.IndexOfFirstMismatch(expected, comparisonMode);
int indexOfMismatch = subject.IndexOfFirstMismatch(expected, comparer);

// If there is no difference it means that expected starts with subject and subject is shorter than expected
if (indexOfMismatch == -1)
Expand Down
21 changes: 10 additions & 11 deletions Src/FluentAssertions/Primitives/StringStartStrategy.cs
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@@ -1,30 +1,29 @@
using System;
using System.Collections.Generic;
using FluentAssertions.Common;
using FluentAssertions.Execution;

namespace FluentAssertions.Primitives;

internal class StringStartStrategy : IStringComparisonStrategy
{
private readonly StringComparison stringComparison;
private readonly IEqualityComparer<string> comparer;
private readonly bool ignoringCase;

public StringStartStrategy(StringComparison stringComparison)
public StringStartStrategy(IEqualityComparer<string> comparer)
{
this.stringComparison = stringComparison;
this.comparer = comparer;
ignoringCase = comparer.Equals("A", "a");
}

public string ExpectationDescription
{
get
{
string predicateDescription = IgnoreCase ? "start with equivalent of" : "start with";
string predicateDescription = ignoringCase ? "start with equivalent of" : "start with";
return "Expected {context:string} to " + predicateDescription + " ";
}
}

private bool IgnoreCase
=> stringComparison == StringComparison.OrdinalIgnoreCase;

public void ValidateAgainstMismatch(IAssertionScope assertion, string subject, string expected)
{
if (!assertion
Expand All @@ -34,13 +33,13 @@ public void ValidateAgainstMismatch(IAssertionScope assertion, string subject, s
return;
}

if (subject.StartsWith(expected, stringComparison))
int indexOfMismatch = subject.IndexOfFirstMismatch(expected, comparer);

if (indexOfMismatch < 0 || indexOfMismatch >= expected.Length)
{
return;
}

int indexOfMismatch = subject.IndexOfFirstMismatch(expected, stringComparison);

assertion.FailWith(
ExpectationDescription + "{0}{reason}, but {1} differs near " + subject.IndexedSegmentAt(indexOfMismatch) +
".",
Expand Down
2 changes: 2 additions & 0 deletions Tests/Approval.Tests/ApprovedApi/FluentAssertions/net47.verified.txt
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Expand Up @@ -2016,6 +2016,7 @@ namespace FluentAssertions.Primitives
public FluentAssertions.AndConstraint<TAssertions> Be(string expected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEquivalentTo(string expected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEquivalentTo(string expected, System.Collections.Generic.IEqualityComparer<string> comparer, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeLowerCased(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeNullOrEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeNullOrWhiteSpace(string because = "", params object[] becauseArgs) { }
Expand All @@ -2042,6 +2043,7 @@ namespace FluentAssertions.Primitives
public FluentAssertions.AndConstraint<TAssertions> NotBe(string unexpected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected, System.Collections.Generic.IEqualityComparer<string> comparer, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeLowerCased(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeNullOrEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeNullOrWhiteSpace(string because = "", params object[] becauseArgs) { }
Expand Down
2 changes: 2 additions & 0 deletions Tests/Approval.Tests/ApprovedApi/FluentAssertions/net6.0.verified.txt
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Expand Up @@ -2100,6 +2100,7 @@ namespace FluentAssertions.Primitives
public FluentAssertions.AndConstraint<TAssertions> Be(string expected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEquivalentTo(string expected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEquivalentTo(string expected, System.Collections.Generic.IEqualityComparer<string> comparer, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeLowerCased(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeNullOrEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeNullOrWhiteSpace(string because = "", params object[] becauseArgs) { }
Expand All @@ -2126,6 +2127,7 @@ namespace FluentAssertions.Primitives
public FluentAssertions.AndConstraint<TAssertions> NotBe(string unexpected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected, System.Collections.Generic.IEqualityComparer<string> comparer, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeLowerCased(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeNullOrEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeNullOrWhiteSpace(string because = "", params object[] becauseArgs) { }
Expand Down
2 changes: 2 additions & 0 deletions Tests/Approval.Tests/ApprovedApi/FluentAssertions/netstandard2.0.verified.txt
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Expand Up @@ -1967,6 +1967,7 @@ namespace FluentAssertions.Primitives
public FluentAssertions.AndConstraint<TAssertions> Be(string expected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEquivalentTo(string expected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeEquivalentTo(string expected, System.Collections.Generic.IEqualityComparer<string> comparer, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeLowerCased(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeNullOrEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> BeNullOrWhiteSpace(string because = "", params object[] becauseArgs) { }
Expand All @@ -1993,6 +1994,7 @@ namespace FluentAssertions.Primitives
public FluentAssertions.AndConstraint<TAssertions> NotBe(string unexpected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeEquivalentTo(string unexpected, System.Collections.Generic.IEqualityComparer<string> comparer, string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeLowerCased(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeNullOrEmpty(string because = "", params object[] becauseArgs) { }
public FluentAssertions.AndConstraint<TAssertions> NotBeNullOrWhiteSpace(string because = "", params object[] becauseArgs) { }
Expand Down