[TESTS] input argument validation.

TODO.md

@@ -62,4 +62,5 @@ TODO
 	-	dido for prediction, how to handle? skip over...
 9. check against `len < 2`!!!
 	-	only a single data point; unless pass through (0,0), then cannot model!
+	-	should it return `null` or error?
 10. 

test/test.js

@@ -24,6 +24,228 @@ describe( 'compute-linear-regression', function tests() {
 		expect( lr ).to.be.a( 'function' );
 	});
 
-	it( 'should do something' );
+	it( 'should throw an error if not provided a data array', function test() {
+		var values = [
+			'5',
+			5,
+			NaN,
+			null,
+			undefined,
+			true,
+			{},
+			function(){}
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( value );
+			};
+		}
+	});
+
+	it( 'should throw an error if not provided an array or an options object as a second argument', function test() {
+		var values = [
+			'5',
+			5,
+			NaN,
+			null,
+			undefined,
+			true,
+			function(){}
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( [[1,1],[2,2]], value );
+			};
+		}
+	});
+
+	it( 'should throw an error if provided a dependent variable which is not an array', function test() {
+		var values = [
+			'5',
+			5,
+			NaN,
+			null,
+			undefined,
+			true,
+			{},
+			function(){}
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( [1,2,3], value, {} );
+			};
+		}
+	});
+
+	it( 'should throw an error if provided an options argument which is not an object', function test() {
+		var values = [
+			'5',
+			5,
+			NaN,
+			null,
+			undefined,
+			true,
+			[],
+			function(){}
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( [1,2], [1,2], value );
+			};
+		}
+	});
+
+	it( 'should throw an error if the independent and dependent variable arrays are of unequal length', function test() {
+		expect( foo ).to.throw( Error );
+		function foo() {
+			lr( [1,2], [1,2,3] );
+		}
+	});
+
+	it( 'should throw an error if provided an accessors option which is not an object', function test() {
+		var values = [
+			'5',
+			5,
+			NaN,
+			null,
+			undefined,
+			true,
+			function(){},
+			[]
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( [1,2], [1,2], {
+					'accessors': value
+				});
+			};
+		}
+	});
+
+	it( 'should throw an error if provided an x-accessor which is not a function', function test() {
+		var values = [
+			'5',
+			5,
+			NaN,
+			null,
+			undefined,
+			true,
+			{},
+			[]
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( [1,2], [1,2], {
+					'accessors': {
+						'x': value
+					}
+				});
+			};
+		}
+	});
+
+	it( 'should throw an error if provided a y-accessor which is not a function', function test() {
+		var values = [
+			'5',
+			5,
+			NaN,
+			null,
+			undefined,
+			true,
+			{},
+			[]
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( [1,2], [1,2], {
+					'accessors': {
+						'y': value
+					}
+				});
+			};
+		}
+	});
+
+	it( 'should throw an error if provided a non-numeric slope', function test() {
+		var values = [
+			'5',
+			function(){},
+			NaN,
+			null,
+			undefined,
+			true,
+			{},
+			[]
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( [1,2], [1,2], {
+					'slope': value
+				});
+			};
+		}
+	});
+
+	it( 'should throw an error if provided a non-numeric intercept', function test() {
+		var values = [
+			'5',
+			function(){},
+			NaN,
+			null,
+			undefined,
+			true,
+			{},
+			[]
+		];
+
+		for ( var i = 0; i < values.length; i++ ) {
+			expect( badValue( values[i] ) ).to.throw( TypeError );
+		}
+		function badValue( value ) {
+			return function() {
+				lr( [1,2], [1,2], {
+					'intercept': value
+				});
+			};
+		}
+	});
+
+	it( 'should return a model object', function test() {
+		assert.isObject( lr( [1,2], [1,2] ) );
+	});
+
+	it( 'should...' );
 
 });