Add support for short tons

src/conversions.rs

@@ -64,6 +64,11 @@ fn get_conversion(unit: NonMetric) -> Conversion {
 			from: pound_from,
 			to: MetricQuantity { amount: 14.0 * pound_to, unit: Metric::Gram },
 		},
+		NonMetric::ShortTon => Conversion {
+			offset: 0.0,
+			from: pound_from,
+			to: MetricQuantity { amount: 2000.0 * pound_to, unit: Metric::Gram },
+		},
 		// Temperature
 		NonMetric::Fahrenheit => Conversion {
 			offset: 32.0,
@@ -184,6 +189,7 @@ mod test {
 			Test(NonMetric::Ounce, 28.349523125),
 			Test(NonMetric::Pound, 453.59237),
 			Test(NonMetric::Stone, 6350.29318),
+			Test(NonMetric::ShortTon, 907184.74),
 		];
 		run_tests(&tests, Metric::Gram);
 	}

src/lib.rs

@@ -77,6 +77,7 @@ fn unit_to_name(unit: NonMetric) -> &'static str {
 		NonMetric::Ounce => "ounces",
 		NonMetric::Pound => "pounds",
 		NonMetric::Stone => "stones",
+		NonMetric::ShortTon => "short tons",
 		// Temperature
 		NonMetric::Fahrenheit => "degrees Fahrenheit",
 		// Area
@@ -129,6 +130,7 @@ mod test {
 		assert_eq!(run("1 oz"), Ok("28.35 g".to_string()));
 		assert_eq!(run("1 lb"), Ok("453.6 g".to_string()));
 		assert_eq!(run("1 st"), Ok("6.35 kg".to_string()));
+		assert_eq!(run("1 short ton"), Ok("907.2 kg".to_string()));
 		// Temperature
 		assert_eq!(run("-40 °F"), Ok("-40 °C".to_string()));
 		assert_eq!(run("0 °F"), Ok("-17.78 °C".to_string()));

src/parse.rs

@@ -98,6 +98,13 @@ fn parse_unit(input: String) -> Result<NonMetric, ParseError> {
 		"stones" => Ok(NonMetric::Stone),
 		"st" => Ok(NonMetric::Stone),
 
+		"short ton" => Ok(NonMetric::ShortTon),
+		"short tons" => Ok(NonMetric::ShortTon),
+		"US ton" => Ok(NonMetric::ShortTon),
+		"US tons" => Ok(NonMetric::ShortTon),
+		"us ton" => Ok(NonMetric::ShortTon),
+		"us tons" => Ok(NonMetric::ShortTon),
+
 		// Temperature
 		"degree Fahrenheit" => Ok(NonMetric::Fahrenheit),
 		"degrees Fahrenheit" => Ok(NonMetric::Fahrenheit),
@@ -463,6 +470,15 @@ mod test {
 			"st",
 		]);
 
+		test_units(NonMetric::ShortTon, &[
+			"short ton",
+			"short tons",
+			"US ton",
+			"US tons",
+			"us ton",
+			"us tons",
+		]);
+
 		// Temperature
 		test_units(NonMetric::Fahrenheit, &[
 			"degree Fahrenheit",

src/units.rs

@@ -19,6 +19,7 @@ pub enum NonMetric {
 	Ounce,
 	Pound,
 	Stone,
+	ShortTon,
 	// Temperature
 	Fahrenheit,
 	// Area