1 files changed, 23 insertions, 0 deletions
diff --git a/tests/FundLab.Web.Tests/ChartTests.fs b/tests/FundLab.Web.Tests/ChartTests.fs
new file mode 100644
index 0000000..cede2d2
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+++ b/tests/FundLab.Web.Tests/ChartTests.fs
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+namespace FundLab.Web.Tests
+
+open Xunit
+open FundLab.Web
+
+module ChartTests =
+
+    [<Fact>]
+    let ``chart points preserve chronological order and normalize NAV values`` () =
+        let observations : NavObservation list =
+            [
+                { navDate = "2026-01-01"; nav = "1.00000000"; dailyReturn = None }
+                { navDate = "2026-01-02"; nav = "1.25000000"; dailyReturn = Some "25.00000000" }
+                { navDate = "2026-01-03"; nav = "1.10000000"; dailyReturn = Some "-12.00000000" }
+            ]
+
+        let points = Chart.chartPoints observations
+
+        Assert.Equal(3, points.Length)
+        Assert.Equal(0.0, points[0].x)
+        Assert.Equal(1.0, points[1].y)
+        Assert.Equal(0.4, points[2].y)
+        Assert.Equal("2026-01-03", points[2].navDate)