test: add tests for sys, html and time stdlib modules (#258)

* test: add tests for sys, html and time stdlib modules

Add test coverage for three stdlib modules that had bindings
but no tests:
- TestSys.fs: platform, version, maxsize, maxunicode, path, argv, byteorder
- TestHtml.fs: escape (with/without quote flag), unescape, roundtrip
- TestTime.fs: time, monotonic, perf_counter, process_time, ctime, sleep, timezone

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* test: address review feedback on sys/time tests

- Remove trivially-true Count >= 0 assertions; assert argv/path are non-empty instead
- Drop redundant |> ignore no-ops
- Remove sys.maxsize test — binding types it as int (Int32) but Python
  value overflows on 64-bit systems, so comparison returns False
- Simplify time.sleep test to just call sleep (no-op assertion removed)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(sys): type maxsize as nativeint instead of int

Python's sys.maxsize is 2^63−1 on 64-bit systems, which overflows Fable's
Int32 (the target type for F# int). nativeint maps to Python's native int,
preserving the full value. Re-adds the maxsize positivity test.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Dag Brattli <dag@brattli.net>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: 4 people

src/stdlib/Sys.fs

@@ -35,7 +35,7 @@ type IExports =
     /// Version information encoded as a single integer
     abstract hexversion: int
     /// Maximum value a variable of type int can take
-    abstract maxsize: int
+    abstract maxsize: nativeint
     /// Maximum Unicode code point value
     abstract maxunicode: int
     /// Module search path - list of directory names where Python looks for modules

test/Fable.Python.Test.fsproj

@@ -27,6 +27,9 @@
     <Compile Include="TestMath.fs" />
     <Compile Include="TestRandom.fs" />
     <Compile Include="TestBase64.fs" />
+    <Compile Include="TestHtml.fs" />
+    <Compile Include="TestSys.fs" />
+    <Compile Include="TestTime.fs" />
     <Compile Include="TestString.fs" />
     <Compile Include="TestPydantic.fs" />
     <Compile Include="TestFastAPI.fs" />

test/TestHtml.fs

@@ -0,0 +1,41 @@
+module Fable.Python.Tests.Html
+
+open Fable.Python.Testing
+open Fable.Python.Html
+
+[<Fact>]
+let ``test html.escape escapes ampersand`` () =
+    html.escape "a & b" |> equal "a &amp; b"
+
+[<Fact>]
+let ``test html.escape escapes less-than`` () =
+    html.escape "<tag>" |> equal "&lt;tag&gt;"
+
+[<Fact>]
+let ``test html.escape escapes double quotes by default`` () =
+    html.escape "\"hello\"" |> equal "&quot;hello&quot;"
+
+[<Fact>]
+let ``test html.escape with quote=false leaves quotes unescaped`` () =
+    html.escape ("\"hello\"", false) |> equal "\"hello\""
+
+[<Fact>]
+let ``test html.escape with quote=true escapes quotes`` () =
+    html.escape ("\"hello\"", true) |> equal "&quot;hello&quot;"
+
+[<Fact>]
+let ``test html.unescape reverses escape`` () =
+    html.unescape "&lt;tag&gt;" |> equal "<tag>"
+
+[<Fact>]
+let ``test html.unescape reverses ampersand`` () =
+    html.unescape "a &amp; b" |> equal "a & b"
+
+[<Fact>]
+let ``test html.unescape reverses quot`` () =
+    html.unescape "&quot;hello&quot;" |> equal "\"hello\""
+
+[<Fact>]
+let ``test html roundtrip`` () =
+    let original = "<div class=\"main\">Hello & World</div>"
+    html.unescape (html.escape original) |> equal original

test/TestSys.fs

@@ -0,0 +1,33 @@
+module Fable.Python.Tests.Sys
+
+open Fable.Python.Testing
+open Fable.Python.Sys
+
+[<Fact>]
+let ``test sys.platform is non-empty string`` () =
+    sys.platform.Length > 0 |> equal true
+
+[<Fact>]
+let ``test sys.version is non-empty string`` () =
+    sys.version.Length > 0 |> equal true
+
+[<Fact>]
+let ``test sys.maxsize is positive`` () =
+    sys.maxsize > 0n |> equal true
+
+[<Fact>]
+let ``test sys.maxunicode is 1114111`` () =
+    sys.maxunicode |> equal 1114111
+
+[<Fact>]
+let ``test sys.path has at least one element`` () =
+    sys.path.Count > 0 |> equal true
+
+[<Fact>]
+let ``test sys.argv has at least one element`` () =
+    sys.argv.Count > 0 |> equal true
+
+[<Fact>]
+let ``test sys.byteorder is little or big`` () =
+    let order = sys.byteorder
+    (order = ByteOrder.Little || order = ByteOrder.Big) |> equal true

test/TestTime.fs

@@ -0,0 +1,49 @@
+module Fable.Python.Tests.Time
+
+open Fable.Python.Testing
+open Fable.Python.Time
+
+[<Fact>]
+let ``test time.time returns positive float`` () =
+    let t = time.time ()
+    t > 0.0 |> equal true
+
+[<Fact>]
+let ``test time.monotonic returns positive float`` () =
+    let t = time.monotonic ()
+    t > 0.0 |> equal true
+
+[<Fact>]
+let ``test time.perf_counter returns positive float`` () =
+    let t = time.perf_counter ()
+    t > 0.0 |> equal true
+
+[<Fact>]
+let ``test time.process_time returns non-negative float`` () =
+    let t = time.process_time ()
+    t >= 0.0 |> equal true
+
+[<Fact>]
+let ``test time.monotonic increases over calls`` () =
+    let t1 = time.monotonic ()
+    let t2 = time.monotonic ()
+    t2 >= t1 |> equal true
+
+[<Fact>]
+let ``test time.ctime returns non-empty string`` () =
+    let s = time.ctime ()
+    s.Length > 0 |> equal true
+
+[<Fact>]
+let ``test time.ctime with seconds returns non-empty string`` () =
+    let s = time.ctime 0.0
+    s.Length > 0 |> equal true
+
+[<Fact>]
+let ``test time.sleep does not throw`` () =
+    time.sleep 0.0
+
+[<Fact>]
+let ``test time.timezone is int`` () =
+    let tz = time.timezone
+    (tz >= -50400 && tz <= 50400) |> equal true