Added the BeyondFacts Lab as a prototype (#1175)

app/Tests/Tools/PluginSystem/CSharpStringLiteralTests.cs

@@ -0,0 +1,127 @@
+using Microsoft.CodeAnalysis.CSharp;
+
+using SharedTools;
+
+namespace AIStudio.Tests.Tools.PluginSystem;
+
+/// <summary>
+/// Checks that the I18N collector reads string literals exactly as the compiler does.
+/// </summary>
+/// <remarks>
+/// The collector files a text under the hash of what it reads, and the app looks it up by the hash of the string the
+/// compiler made. Every case therefore compares the reader with Roslyn, the compiler itself.
+/// </remarks>
+[TestFixture]
+public sealed class CSharpStringLiteralTests
+{
+    private static readonly string[] LITERALS =
+    [
+        // Regular literals, with every kind of escape sequence:
+        "\"Plain text\"",
+        "\"\"",
+        "\"Quotes \\\" and a backslash \\\\\"",
+        "\"Line\\nbreak and tab\\t and return\\r\"",
+        "\"All simple escapes: \\' \\0 \\a \\b \\e \\f \\v\"",
+        "\"Unicode \\u00FC and \\U0001F600\"",
+        "\"Hex \\x41, \\x041, \\x0041, and \\xA followed by text\"",
+        "\"Commas, \\\"quoted\\\", and parentheses (like this)\"",
+
+        // Verbatim literals:
+        "@\"C:\\Users\\Name\"",
+        "@\"Doubled \"\"quotes\"\" inside\"",
+        "@\"Over\nseveral\r\nlines\"",
+
+        // Single-line raw literals:
+        "\"\"\"Text with \"quotes\" inside\"\"\"",
+        "\"\"\"By clicking \"Accept GPL and Install,\" you agree\"\"\"",
+        "\"\"\"\"Text with \"\"\" inside\"\"\"\"",
+        "\"\"\"{} and \\n stay as they are\"\"\"",
+
+        // Multi-line raw literals:
+        "\"\"\"\n    ## Welcome!\n\n    The first paragraph.\n    \"\"\"",
+        "\"\"\"\r\n    CRLF line endings\r\n    stay as they are\r\n    \"\"\"",
+        "\"\"\"\n        Indented\n            more indented\n        back\n        \"\"\"",
+        "\"\"\"\n    Before an empty line\n\n    after it\n    \"\"\"",
+        "\"\"\"\n    Before a line of spaces\n  \n    after it\n    \"\"\"",
+        "\"\"\"\n    Before a line of more spaces\n        \n    after it\n    \"\"\"",
+        "\"\"\"   \n    Spaces after the opening quotes\n    \"\"\"",
+        "\"\"\"\n\tTabs as indentation\n\t\"\"\"",
+        "\"\"\"\n    Quotes \"\" inside, and \"quoted\" text\n    \"\"\"",
+        "\"\"\"\"\n    Three quotes \"\"\" inside\n    \"\"\"\"",
+        "\"\"\"\nNo indentation at all\n\"\"\"",
+    ];
+
+    private static readonly string[] NO_LITERALS =
+    [
+        "Text without quotes",
+        "$\"Interpolated {value}\"",
+        "\"Unterminated",
+        "\"Line break\n inside a regular literal\"",
+        "\"Unknown escape \\q\"",
+        "\"Short unicode \\u12\"",
+        "@\"Unterminated verbatim",
+        "\"\"\"Unterminated raw",
+        "\"\"\"\n    Content after the closing line is missing",
+        "\"\"\"\n      Less indented than\n    the closing line is not allowed\n      \"\"\"",
+    ];
+
+    [TestCaseSource(nameof(LITERALS))]
+    public void TheReaderGetsWhatTheCompilerGets(string literal)
+    {
+        var token = SyntaxFactory.ParseToken(literal);
+        Assume.That(token.ContainsDiagnostics, Is.False, "The case itself is no valid literal.");
+
+        var isRead = CSharpStringLiteral.TryRead($"{literal}) and more code", out var value, out var length);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(isRead, Is.True);
+            Assert.That(value, Is.EqualTo(token.ValueText));
+            Assert.That(length, Is.EqualTo(token.Span.Length));
+        }
+    }
+
+    [TestCaseSource(nameof(NO_LITERALS))]
+    public void SomethingTheCompilerRefusesOrComputesAtRuntimeIsNotRead(string source)
+    {
+        Assert.That(CSharpStringLiteral.TryRead(source, out _, out _), Is.False);
+    }
+
+    [Test]
+    public void TheCasesWhichAreNoLiteralsAreRefusedByTheCompilerAsWell()
+    {
+        using (Assert.EnterMultipleScope())
+        {
+            foreach (var source in NO_LITERALS.Where(source => source.StartsWith('"') || source.StartsWith("@\"", StringComparison.Ordinal)))
+            {
+                var token = SyntaxFactory.ParseToken(source);
+                Assert.That(token.ContainsDiagnostics || token.Span.Length < source.Length, Is.True, $"The compiler accepts: {source}");
+            }
+        }
+    }
+
+    [Test]
+    public void TheLiteralEndsWhereTheCompilerEndsIt()
+    {
+        const string SOURCE = "\"First\", \"Second\")";
+
+        var isRead = CSharpStringLiteral.TryRead(SOURCE, out var value, out var length);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(isRead, Is.True);
+            Assert.That(value, Is.EqualTo("First"));
+            Assert.That(SOURCE[length..], Is.EqualTo(", \"Second\")"));
+        }
+    }
+
+    [Test]
+    public void EveryLiteralIsAValidStringToken()
+    {
+        using (Assert.EnterMultipleScope())
+        {
+            foreach (var literal in LITERALS)
+                Assert.That(SyntaxFactory.ParseToken(literal).Kind(), Is.AnyOf(SyntaxKind.StringLiteralToken, SyntaxKind.SingleLineRawStringLiteralToken, SyntaxKind.MultiLineRawStringLiteralToken), literal);
+        }
+    }
+}