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Add explicit test for hash collision handling. #11

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Merged
jlao merged 1 commit into from
Mar 10, 2019
Merged

Add explicit test for hash collision handling. #11

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13 changes: 13 additions & 0 deletions UnitTests/BadHashCode.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
namespace UnitTests
{
struct BadHashCode
{
public int Value;

public override int GetHashCode() => 42;

public static implicit operator BadHashCode(int i) => new BadHashCode { Value = i };

public static implicit operator int(BadHashCode bhc) => bhc.Value;
}
}
49 changes: 36 additions & 13 deletions UnitTests/CacheTableTestBase.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@

namespace UnitTests
{
public abstract class CacheTableTestBase<TCacheTable> where TCacheTable : ICacheTable<int, int>
public abstract class CacheTableTestBase
{
protected ITestOutputHelper output;

Expand All @@ -17,12 +17,12 @@ protected CacheTableTestBase(ITestOutputHelper output)
this.output = output;
}

protected abstract TCacheTable CreateTable(int numRows, int numColumns);
protected abstract ICacheTable<TKey, TValue> CreateTable<TKey, TValue>(int numRows, int numColumns);

[Fact]
public void SetAndTryGetValue()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
table[1] = 2;
table.TryGetValue(1, out int val).Should().BeTrue();
val.Should().Be(2);
Expand All @@ -31,23 +31,23 @@ public void SetAndTryGetValue()
[Fact]
public void TryGetNonExistentValue()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
table.TryGetValue(1, out int val).Should().BeFalse();
val.Should().Be(default(int));
}

[Fact]
public void SetAndIndex()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
table[1] = 2;
table[1].Should().Be(2);
}

[Fact]
public void Update()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);

for (int i = 0; i < 4; i++)
{
Expand All @@ -72,7 +72,7 @@ public void Update()
[Fact]
public void IndexNonExistentKeyThrows()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
Action act = () => Console.WriteLine(table[0]);
act.Should().Throw<KeyNotFoundException>()
.WithMessage("No value found for 0");
Expand All @@ -81,7 +81,7 @@ public void IndexNonExistentKeyThrows()
[Fact]
public void ContainsKey()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
table.ContainsKey(0).Should().BeFalse();
table[0] = 1;
table.ContainsKey(0).Should().BeTrue();
Expand All @@ -90,7 +90,7 @@ public void ContainsKey()
[Fact]
public void Remove()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
table[1] = 2;
table.Remove(1).Should().BeTrue();
table.TryGetValue(1, out int val).Should().BeFalse();
Expand All @@ -103,7 +103,7 @@ public void Clear()
{
const int numInserts = 40;

var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
for (int i = 0; i < numInserts; i++)
{
table[i] = i;
Expand All @@ -123,7 +123,7 @@ public void Clear()
[Fact]
public void Count()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
table.Count.Should().Be(0);

for (int i = 0; i < 4; i++)
Expand All @@ -142,7 +142,7 @@ public void Count()
[Fact]
public void Enumerate()
{
var table = this.CreateTable(10, 4);
var table = this.CreateTable<int, int>(10, 4);
var rng = new Random();
List<KeyValuePair<int, int>> expected = new List<KeyValuePair<int, int>>();

Expand All @@ -160,7 +160,7 @@ public void Enumerate()
[Fact]
public void InsertOnFullTableOverwrites()
{
var table = this.CreateTable(5, 4);
var table = this.CreateTable<int, int>(5, 4);

int i = 0;
do
Expand All @@ -183,5 +183,28 @@ public void InsertOnFullTableOverwrites()
after.Count.Should().Be(1);
after.First().Should().Be(i);
}

[Theory]
[InlineData(4)]
[InlineData(7)]
public void ResolvesHashCollisions(int numColumns)
{
var table = this.CreateTable<BadHashCode, int>(5, numColumns);

for (int i = 0; i < numColumns; i++)
{
table[i] = i;
}

for (int i = 0; i < numColumns; i++)
{
table[i].Should().Be(i);
}

// This is going to overwrite a value
table[numColumns] = numColumns;
table[numColumns].Should().Be(numColumns);
table.Count.Should().Be(numColumns);
}
}
}
6 changes: 3 additions & 3 deletions UnitTests/CacheTableTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,15 +3,15 @@

namespace UnitTests
{
public class CacheTableTests : CacheTableTestBase<CacheTable<int, int>>
public class CacheTableTests : CacheTableTestBase
{
public CacheTableTests(ITestOutputHelper output) : base(output)
{
}

protected override CacheTable<int, int> CreateTable(int numRows, int numColumns)
protected override ICacheTable<TKey, TValue> CreateTable<TKey, TValue>(int numRows, int numColumns)
{
return new CacheTable<int, int>(numRows, numColumns);
return new CacheTable<TKey, TValue>(numRows, numColumns);
}
}
}
8 changes: 4 additions & 4 deletions UnitTests/ConcurrentCacheTableTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,21 +6,21 @@

namespace UnitTests
{
public class ConcurrentCacheTableTests : CacheTableTestBase<ConcurrentCacheTable<int, int>>
public class ConcurrentCacheTableTests : CacheTableTestBase
{
public ConcurrentCacheTableTests(ITestOutputHelper output) : base(output)
{
}

protected override ConcurrentCacheTable<int, int> CreateTable(int numRows, int numColumns)
protected override ICacheTable<TKey, TValue> CreateTable<TKey, TValue>(int numRows, int numColumns)
{
return new ConcurrentCacheTable<int, int>(numRows, numColumns, 3);
return new ConcurrentCacheTable<TKey, TValue>(numRows, numColumns, 3);
}

[Fact]
public async Task ConcurrentWrites()
{
var table = CreateTable(5, 4);
var table = this.CreateTable<int, int>(5, 4);

const int numWrites = 1000;

Expand Down