feat(growth): add weight-for-height calculation

test/growth/score/weight_for_height_test.exs

@@ -0,0 +1,142 @@
+# test/growth/score/weight_for_height_test.exs
+defmodule Growth.Score.WeightForHeightTest do
+  use ExUnit.Case, async: true
+
+  alias Growth
+  alias Growth.Score.WeightForHeight
+
+  describe "measure_name/0" do
+    test "returns the correct measure name atom" do
+      assert WeightForHeight.measure_name() == :weight_for_height
+    end
+  end
+
+  describe "lms/2" do
+    test "returns LMS values for exact height match" do
+      growth = %Growth{
+        gender: :male,
+        weight: 7.3,
+        height: 65.0,
+        name: "Joe Doe",
+        date_of_measurement: Date.utc_today(),
+        date_of_birth: Date.shift(Date.utc_today(), day: -91)
+      }
+
+      assert WeightForHeight.lms(growth, WeightForHeight) == [
+               {"height", {-0.35210000000000002, 7.4326999999999996, 0.082170000000000007}}
+             ]
+    end
+
+    test "returns LMS values for closest height match when exact is not found" do
+      growth = %Growth{
+        gender: :male,
+        weight: 7.3,
+        height: 64.9,
+        name: "Joe Doe",
+        date_of_measurement: Date.utc_today(),
+        date_of_birth: Date.shift(Date.utc_today(), day: -91)
+      }
+
+      assert WeightForHeight.lms(growth, WeightForHeight) == [
+               {"height", {-0.35210000000000002, 7.4326999999999996, 0.082170000000000007}}
+             ]
+
+      growth_closer_to_higher = %Growth{
+        gender: :male,
+        weight: 7.4,
+        height: 65.09,
+        name: "Joe Doe",
+        date_of_measurement: Date.utc_today(),
+        date_of_birth: Date.shift(Date.utc_today(), day: -91)
+      }
+
+      assert WeightForHeight.lms(growth_closer_to_higher, WeightForHeight) == [
+               {"height", {-0.35210000000000002, 7.4562999999999997, 0.082159999999999997}}
+             ]
+    end
+
+    test "returns empty list if weight or height is missing" do
+      growth_no_weight = %Growth{
+        gender: :male,
+        height: 60.0,
+        name: "Joe Doe",
+        date_of_measurement: Date.utc_today(),
+        date_of_birth: Date.shift(Date.utc_today(), day: -91)
+      }
+
+      assert WeightForHeight.lms(growth_no_weight, WeightForHeight) == []
+
+      growth_no_height = %Growth{
+        gender: :male,
+        weight: 5.0,
+        name: "Joe Doe",
+        date_of_measurement: Date.utc_today(),
+        date_of_birth: Date.shift(Date.utc_today(), day: -91)
+      }
+
+      assert WeightForHeight.lms(growth_no_height, WeightForHeight) == []
+
+      growth_nil_values = %Growth{
+        gender: :male,
+        weight: nil,
+        height: nil,
+        name: "Joe Doe",
+        date_of_measurement: Date.utc_today(),
+        date_of_birth: Date.shift(Date.utc_today(), day: -91)
+      }
+
+      assert WeightForHeight.lms(growth_nil_values, WeightForHeight) == []
+    end
+
+    test "returns empty list if no matching gender data exists" do
+      # Assuming no :unknown gender data was inserted
+      growth = %Growth{
+        gender: :unknown,
+        weight: 5.0,
+        height: 60.0,
+        name: "Joe Doe",
+        date_of_measurement: Date.utc_today(),
+        date_of_birth: Date.shift(Date.utc_today(), day: -91)
+      }
+
+      assert WeightForHeight.lms(growth, WeightForHeight) == []
+    end
+  end
+
+  describe "find_closest_height/2" do
+    test "finds the lower closest height" do
+      assert WeightForHeight.find_closest_height(:male, 64.99) == [
+               {"height", {-0.35210000000000002, 7.4326999999999996, 0.082170000000000007}}
+             ]
+    end
+
+    test "finds the higher closest height" do
+      assert WeightForHeight.find_closest_height(:male, 65.61) == [
+               {"height", {-0.35210000000000002, 7.5738000000000003, 0.082140000000000005}}
+             ]
+    end
+
+    test "finds the lower closest height when exactly midway" do
+      expected_lms =
+        [
+          [{"height", {-0.35210000000000002, 7.5034000000000001, 0.082150000000000001}}],
+          [{"height", {-0.35210000000000002, 7.4798999999999998, 0.082159999999999997}}]
+        ]
+
+      lms = WeightForHeight.find_closest_height(:male, 65.25)
+      assert Enum.any?(expected_lms, fn entity_lms -> entity_lms == lms end)
+    end
+
+    test "do not match when below minimum height" do
+      assert WeightForHeight.find_closest_height(:male, 44.0) == []
+    end
+
+    test "do not match when above maximum height" do
+      assert WeightForHeight.find_closest_height(:male, 121.0) == []
+    end
+
+    test "returns empty list when no data exists for the gender" do
+      assert WeightForHeight.find_closest_height(:unknown, 60.0) == []
+    end
+  end
+end