Trim blank lines after the header in CR-only documents

Frontmatter.Test/LineEndingTests.cs

@@ -83,4 +83,39 @@ public void RemoveFrontmatter_KeepsTheInputLineEnding(string nl)
 
 		Assert.AreEqual(Lines(nl, "line1", "line2"), result);
 	}
+
+	[TestMethod]
+	[DataRow("\r\n", DisplayName = "CRLF")]
+	[DataRow("\n", DisplayName = "LF")]
+	[DataRow("\r", DisplayName = "CR")]
+	public void ExtractBody_DropsBlankLinesAfterTheHeader_ForEveryLineEnding(string nl)
+	{
+		string input = Lines(nl, "---", "title: x", "---", string.Empty, string.Empty, "Body");
+
+		Assert.AreEqual("Body", Frontmatter.ExtractBody(input));
+	}
+
+	[TestMethod]
+	[DataRow("\r\n", DisplayName = "CRLF")]
+	[DataRow("\n", DisplayName = "LF")]
+	[DataRow("\r", DisplayName = "CR")]
+	public void RemoveFrontmatter_DropsBlankLinesAfterTheHeader_ForEveryLineEnding(string nl)
+	{
+		string input = Lines(nl, "---", "title: x", "---", string.Empty, string.Empty, "Body");
+
+		Assert.AreEqual(Lines(nl, "Body"), Frontmatter.RemoveFrontmatter(input));
+	}
+
+	[TestMethod]
+	[DataRow("\r\n", DisplayName = "CRLF")]
+	[DataRow("\n", DisplayName = "LF")]
+	[DataRow("\r", DisplayName = "CR")]
+	public void ReplaceFrontmatter_DropsBlankLinesAfterTheHeader_ForEveryLineEnding(string nl)
+	{
+		string input = Lines(nl, "---", "title: x", "---", string.Empty, string.Empty, "Body");
+
+		string result = Frontmatter.ReplaceFrontmatter(input, new Dictionary<string, object> { ["title"] = "y" });
+
+		Assert.AreEqual(Lines(nl, "---", "title: y", "---", "Body"), result);
+	}
 }

Frontmatter/Frontmatter.cs

@@ -138,7 +138,7 @@
 		}
 
 		List<Dictionary<string, object>> frontmatterObjects = ExtractFrontmatterObjects(input, out _);
 		return frontmatterObjects.Count > 0 ? frontmatterObjects.First() : null;
 	}
 
 	/// <summary>
@@ -301,7 +301,7 @@
 		}
 
 		// Then add any remaining properties that weren't in the standard order
 		foreach (KeyValuePair<string, object> property in frontmatter)
 		{
 			if (!sortedFrontmatter.ContainsKey(property.Key))
 			{
@@ -351,7 +351,7 @@
 				continue;
 			}
 
 			if (YamlSerializer.TryParseYamlObject(section, out Dictionary<string, object>? frontmatterObject) && frontmatterObject != null)
 			{
 				frontmatterObjects.Add(frontmatterObject);
 			}
@@ -499,7 +499,7 @@
 			lines.Add((start, i));
 			if (c == '\r' && i + 1 < input.Length && input[i + 1] == '\n')
 			{
 				i++;
 			}
 
 			start = i + 1;
@@ -524,7 +524,7 @@
 		for (int i = start; i < body.Length; i++)
 		{
 			char c = body[i];
-			if (c == '\n')
+			if (c is '\n' or '\r')
 			{
 				start = i + 1;
 			}
@@ -618,7 +618,7 @@
 		}
 
 		// Then, add properties from dictionary b that don't exist in a
 		foreach (KeyValuePair<string, object> kvp in b)
 		{
 			if (!combinedFrontmatterObject.ContainsKey(kvp.Key))
 			{