[Repo Assist] test: add 23 unit tests for HtmlInference.inferListType and inferHeaders

tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj

@@ -44,6 +44,7 @@
     <Compile Include="HtmlAttributeExtensions.fs" />
     <Compile Include="HtmlCssSelectors.fs" />
     <Compile Include="HtmlTableCell.fs" />
+    <Compile Include="HtmlInference.fs" />
     <Compile Include="StructuralInference.fs" />
     <Compile Include="StructuralTypes.fs" />
     <Compile Include="BaseTypesHtmlDocument.fs" />

tests/FSharp.Data.Core.Tests/HtmlInference.fs

@@ -0,0 +1,180 @@
+module FSharp.Data.Tests.HtmlInference
+
+open System
+open System.Globalization
+open NUnit.Framework
+open FsUnit
+open FSharp.Data
+open FSharp.Data.Runtime
+open FSharp.Data.Runtime.StructuralTypes
+open FSharp.Data.Runtime.StructuralInference
+
+// ─── Helpers ────────────────────────────────────────────────────────────────
+
+let private mkParams preferOptionals : HtmlInference.Parameters =
+    { MissingValues = TextConversions.DefaultMissingValues
+      CultureInfo = CultureInfo.InvariantCulture
+      UnitsOfMeasureProvider = defaultUnitsOfMeasureProvider
+      PreferOptionals = preferOptionals
+      InferenceMode = InferenceMode'.ValuesOnly }
+
+let private defaultParams = mkParams false
+let private optionalParams = mkParams true
+
+let private prim typ =
+    InferedType.Primitive(typ, None, false, false)
+
+// ─── inferListType ───────────────────────────────────────────────────────────
+
+[<Test>]
+let ``inferListType returns Null for empty array`` () =
+    HtmlInference.inferListType defaultParams [||] |> should equal InferedType.Null
+
+[<Test>]
+let ``inferListType returns Null for whitespace-only values`` () =
+    HtmlInference.inferListType defaultParams [| "  "; "\t"; "" |]
+    |> should equal InferedType.Null
+
+[<Test>]
+let ``inferListType treats nbsp as missing value`` () =
+    HtmlInference.inferListType defaultParams [| "&nbsp;"; "&nbsp" |]
+    |> should equal InferedType.Null
+
+[<Test>]
+let ``inferListType infers int type`` () =
+    HtmlInference.inferListType defaultParams [| "1"; "2"; "3" |]
+    |> should equal (prim typeof<int>)
+
+[<Test>]
+let ``inferListType infers decimal type`` () =
+    HtmlInference.inferListType defaultParams [| "1.5"; "2.3"; "3.7" |]
+    |> should equal (prim typeof<decimal>)
+
+[<Test>]
+let ``inferListType infers float type for scientific notation`` () =
+    HtmlInference.inferListType defaultParams [| "1e100"; "2.5e-10" |]
+    |> should equal (prim typeof<float>)
+
+[<Test>]
+let ``inferListType infers string type`` () =
+    HtmlInference.inferListType defaultParams [| "hello"; "world" |]
+    |> should equal (prim typeof<string>)
+
+[<Test>]
+let ``inferListType infers bool type`` () =
+    HtmlInference.inferListType defaultParams [| "true"; "false" |]
+    |> should equal (prim typeof<bool>)
+
+[<Test>]
+let ``inferListType widens int to decimal when mixed with decimal`` () =
+    HtmlInference.inferListType defaultParams [| "1"; "2.5"; "3" |]
+    |> should equal (prim typeof<decimal>)
+
+[<Test>]
+let ``inferListType widens to float for scientific notation mixed with int`` () =
+    HtmlInference.inferListType defaultParams [| "1"; "1.5e10"; "3" |]
+    |> should equal (prim typeof<float>)
+
+[<Test>]
+let ``inferListType produces Heterogeneous type for mixed numeric and non-numeric`` () =
+    let result = HtmlInference.inferListType defaultParams [| "42"; "hello" |]
+
+    match result with
+    | InferedType.Heterogeneous _ -> ()
+    | _ -> Assert.Fail(sprintf "Expected Heterogeneous, got %A" result)
+
+[<Test>]
+let ``inferListType treats NaN as float when preferOptionals is false`` () =
+    let result = HtmlInference.inferListType defaultParams [| "NaN" |]
+    result |> should equal (prim typeof<float>)
+
+[<Test>]
+let ``inferListType treats NaN as Null when preferOptionals is true`` () =
+    let result = HtmlInference.inferListType optionalParams [| "NaN" |]
+    result |> should equal InferedType.Null
+
+[<Test>]
+let ``inferListType treats NA as float when preferOptionals is false`` () =
+    let result = HtmlInference.inferListType defaultParams [| "NA" |]
+    result |> should equal (prim typeof<float>)
+
+[<Test>]
+let ``inferListType infers date type for ISO date strings`` () =
+    let result =
+        HtmlInference.inferListType defaultParams [| "2023-01-01"; "2023-06-15" |]
+
+    match result with
+    | InferedType.Primitive(typ, _, false, _) ->
+        (typ = typeof<DateTime> || typ = typeof<DateOnly>)
+        |> should equal true
+    | _ -> Assert.Fail(sprintf "Expected date primitive, got %A" result)
+
+[<Test>]
+let ``inferListType with mixed missing and integer values infers float (allowEmptyValues path)`` () =
+    // NaN + int values → float because NaN is treated as float when preferOptionals=false
+    let result = HtmlInference.inferListType defaultParams [| "NaN"; "1"; "2" |]
+    result |> should equal (prim typeof<float>)
+
+[<Test>]
+let ``inferListType with single integer value returns int`` () =
+    HtmlInference.inferListType defaultParams [| "42" |]
+    |> should equal (prim typeof<int>)
+
+// ─── inferHeaders ────────────────────────────────────────────────────────────
+
+[<Test>]
+let ``inferHeaders returns false for empty rows`` () =
+    let hasHeaders, names, units, _ = HtmlInference.inferHeaders defaultParams [||]
+    hasHeaders |> should equal false
+    names |> should equal None
+    units |> should equal None
+
+[<Test>]
+let ``inferHeaders returns false for single row`` () =
+    let hasHeaders, names, _, _ =
+        HtmlInference.inferHeaders defaultParams [| [| "Name"; "Age" |] |]
+
+    hasHeaders |> should equal false
+    names |> should equal None
+
+[<Test>]
+let ``inferHeaders returns false for exactly two rows`` () =
+    let rows = [| [| "Name"; "Age" |]; [| "Alice"; "30" |] |]
+    let hasHeaders, names, _, _ = HtmlInference.inferHeaders defaultParams rows
+    hasHeaders |> should equal false
+    names |> should equal None
+
+[<Test>]
+let ``inferHeaders returns true when header row differs from data rows`` () =
+    // First row is text (string) headers, data rows are numeric → types differ → headers detected
+    let rows =
+        [| [| "Name"; "Score" |]
+           [| "Alice"; "95" |]
+           [| "Bob"; "87" |] |]
+
+    let hasHeaders, names, _, _ = HtmlInference.inferHeaders defaultParams rows
+    hasHeaders |> should equal true
+    names |> should equal (Some [| "Name"; "Score" |])
+
+[<Test>]
+let ``inferHeaders returns false when all rows have same type`` () =
+    // All rows are strings → header row type = data rows type → no headers inferred
+    let rows =
+        [| [| "Alice"; "Bob" |]
+           [| "Carol"; "Dave" |]
+           [| "Eve"; "Frank" |] |]
+
+    let hasHeaders, names, _, _ = HtmlInference.inferHeaders defaultParams rows
+    hasHeaders |> should equal false
+    names |> should equal None
+
+[<Test>]
+let ``inferHeaders returns inferred type for data rows`` () =
+    let rows =
+        [| [| "Name"; "Age" |]
+           [| "Alice"; "30" |]
+           [| "Bob"; "25" |] |]
+
+    let hasHeaders, _, _, dataType = HtmlInference.inferHeaders defaultParams rows
+    hasHeaders |> should equal true
+    dataType |> should not' (equal None)