TypeScriptToLua · Perryvw · Jan 13, 2022 · Jan 7, 2022 · Jan 10, 2022
diff --git a/src/LuaLib.ts b/src/LuaLib.ts
@@ -44,6 +44,7 @@ export enum LuaLibFeature {
     Iterator = "Iterator",
     Map = "Map",
     MathAtan2 = "MathAtan2",
+    MathSign = "MathSign",
     New = "New",
     Number = "Number",
     NumberIsFinite = "NumberIsFinite",

diff --git a/src/lualib/MathSign.ts b/src/lualib/MathSign.ts
@@ -0,0 +1,9 @@
+function __TS__MathSign(this: void, val: number) {
+    if (val > 0) {
+        return 1;
+    } else if (val < 0) {
+        return -1;
+    }
+
+    return 0;
+}
diff --git a/src/transformation/builtins/math.ts b/src/transformation/builtins/math.ts
@@ -78,6 +78,10 @@ export function transformMathCall(
             return lua.createCallExpression(lua.createTableIndexExpression(math, floor), [add], node);
         }
 
+        case "sign": {
+            return transformLuaLibFunction(context, LuaLibFeature.MathSign, node, ...params);
+        }
+
         case "abs":
         case "acos":
         case "asin":

diff --git a/test/unit/builtins/__snapshots__/math.spec.ts.snap b/test/unit/builtins/__snapshots__/math.spec.ts.snap
diff --git a/test/unit/builtins/math.spec.ts b/test/unit/builtins/math.spec.ts
@@ -1,28 +1,75 @@
 import * as tstl from "../../../src";
 import * as util from "../../util";
 
+// These test are kept to a minimum,
+// because we just want to confirm translation is correct
+// and not test Lua's built in math functions.
+// Differences in math implementations between JS & Lua cause inaccuracies
+// therefore test input numbers are "carefully" selected to always match accuratly.
+// Lualib implementations are tested separately.
 test.each([
-    "Math.cos()",
-    "Math.sin()",
-    "Math.min()",
-    "Math.log2(3)",
-    "Math.log10(3)",
-    "const x = Math.log2(3)",
-    "const x = Math.log10(3)",
-    "Math.log1p(3)",
-    "Math.round(3.3)",
+    // log
+    "Math.log(42)",
+    "Math.log10(10)",
+    "Math.log2(42)",
+    "Math.log1p(42)",
+    // round
+    "Math.round(0.1)",
+    "Math.round(0.9)",
+    "Math.round(0.5)",
+    // abs
+    "Math.abs(-42)",
+    "Math.abs(42)",
+    // trigometric
+    "Math.acos(0.42)",
+    "Math.asin(0.42)",
+    "Math.atan(0.42)",
+    "Math.cos(42)",
+    "Math.sin(42)",
+    "Math.tan(42)",
     "Math.PI",
+    // ceil & floor
+    "Math.ceil(42.42)",
+    "Math.floor(42.42)",
+    // exp
+    "Math.exp(42)",
+    // max & min
+    "Math.max(-42, 42)",
+    "Math.max(42, -42)",
+    "Math.max(42, 42)",
+    "Math.max(-42, -42)",
+    "Math.min(42, -42)",
+    "Math.min(-42, 42)",
+    "Math.min(42, 42)",
+    "Math.min(-42, -42)",
+    // pow
+    "Math.pow(4.2, 4.2)",
+    "Math.pow(4.2, -4.2)",
+    "Math.pow(-4.2, -4.2)",
+    // random
+    // "Math.random()",
+    // sqrt
+    "Math.sqrt(2)",
+    "Math.sqrt(-2)",
 ])("%s", code => {
-    // TODO: Remove?
-    util.testFunction(code).disableSemanticCheck().expectLuaToMatchSnapshot();
+    util.testExpression(code).expectToMatchJsResult();
 });
 
+// Hard to test properly
+util.testExpression("Math.random()").expectNoExecutionError();
+
 test.each(["E", "LN10", "LN2", "LOG10E", "LOG2E", "SQRT1_2", "SQRT2"])("Math.%s", constant => {
     util.testExpression`Math.${constant}`.tap(builder => {
         expect(builder.getLuaExecutionResult()).toBeCloseTo(builder.getJsExecutionResult());
     });
 });
 
+// LuaLib MathSign
+test.each(["Math.sign(-42)", "Math.sign(42)", "Math.sign(-4.2)", "Math.sign(4.2)", "Math.sign(0)"])("%s", code => {
+    util.testExpression(code).expectToMatchJsResult();
+});
+
+// LuaLib Atan2
 const expectMathAtan2: util.TapCallback = builder => expect(builder.getMainLuaCodeChunk()).toContain("math.atan2(");
 const expectMathAtan: util.TapCallback = builder => expect(builder.getMainLuaCodeChunk()).toContain("math.atan(");
 const expectLualibMathAtan2: util.TapCallback = builder =>