test: migrate stats/incr/nancovariance to ULP-based assertions

lib/node_modules/@stdlib/stats/incr/nancovariance/test/test.js

@@ -21,8 +21,7 @@
 // MODULES //
 
 var tape = require( 'tape' );
-var abs = require( '@stdlib/math/base/special/abs' );
-var EPS = require( '@stdlib/constants/float64/eps' );
+var isAlmostSameValue = require( '@stdlib/assert/is-almost-same-value' );
 var incrnancovariance = require( './../lib' );
 
 
@@ -36,17 +35,17 @@ tape( 'main export is a function', function test( t ) {
 
 tape( 'the function returns an accumulator function', function test( t ) {
 	var acc = incrnancovariance();
-	t.strictEqual( typeof acc, 'function', 'returns a function' );
+	t.strictEqual( typeof acc, 'function', 'returns expected value' );
 	t.end();
 });
 
 tape( 'the accumulator function returns null if no valid pairs have been provided', function test( t ) {
 	var acc = incrnancovariance();
-	t.equal( acc(), null, 'returns null initially' );
+	t.strictEqual( acc(), null, 'returns expected value' );
 
 	// Provide an invalid pair:
 	acc( NaN, 5.0 );
-	t.equal( acc(), null, 'still null after invalid pair' );
+	t.strictEqual( acc(), null, 'returns expected value' );
 	t.end();
 });
 
@@ -55,71 +54,77 @@ tape( 'the accumulator function returns null if only one valid pair has been pro
 
 	// Add the first valid pair:
 	acc( 2.0, 1.0 );
-	t.equal( acc(), null, 'returns null for single valid pair' );
+	t.strictEqual( acc(), null, 'returns expected value' );
 	t.end();
 });
 
 tape( 'the accumulator function computes sample covariance once two valid pairs have been provided', function test( t ) {
-	var acc = incrnancovariance();
+	var acc;
 	var cov;
 
+	acc = incrnancovariance();
+
 	// Pair #1:
 	cov = acc( 2.0, 1.0 );
-	t.equal( cov, null, 'still null with only one valid pair' );
+	t.strictEqual( cov, null, 'returns expected value' );
 
 	// Pair #2:
 	cov = acc( 4.0, 5.0 );
-	t.equal( cov, 4.0, 'returns sample covariance after second valid pair' );
+	t.strictEqual( cov, 4.0, 'returns expected value' );
 
 	// Current covariance with no arguments:
-	t.equal( acc(), 4.0, 'returns current covariance' );
+	t.strictEqual( acc(), 4.0, 'returns expected value' );
 	t.end();
 });
 
 tape( 'the accumulator function skips pairs containing NaN', function test( t ) {
-	var acc = incrnancovariance();
+	var acc;
 	var cov;
 
+	acc = incrnancovariance();
+
 	// Provide first valid pair:
 	cov = acc( 2.0, 1.0 );
-	t.equal( cov, null, 'null with only one valid pair' );
+	t.strictEqual( cov, null, 'returns expected value' );
 
 	// Invalid pair => skip:
 	cov = acc( NaN, 10.0 );
-	t.equal( cov, null, 'still null, as second pair is invalid' );
+	t.strictEqual( cov, null, 'returns expected value' );
 
 	// Provide second valid pair:
 	cov = acc( 2.0, 5.0 );
+
 	// For (2,1) and (2,5): same X => covariance=0
-	t.equal( cov, 0.0, 'returns 0.0 for these pairs' );
+	t.strictEqual( cov, 0.0, 'returns expected value' );
 
 	// Provide third valid pair:
 	cov = acc( 5.0, 9.0 );
-	t.equal( typeof cov, 'number', 'returns a number after third valid pair' );
+	t.strictEqual( typeof cov, 'number', 'returns expected value' );
 	t.end();
 });
 
 tape( 'the accumulator function computes correct covariance for multiple valid pairs interspersed with invalid pairs', function test( t ) {
-	var expected = 14.0/3.0;
-	var delta;
-	var data = [
+	var expected;
+	var data;
+	var acc;
+	var cov;
+	var i;
+
+	data = [
 		[ 2.0, 1.0 ],
 		[ NaN, 4.0 ],
 		[ 4.0, 5.0 ],
 		[ 3.0, 7.0 ],
 		[ NaN, NaN ],
 		[ 5.0, 11.0 ]
 	];
-	var acc = incrnancovariance();
-	var cov;
-	var tol;
-	var i;
+	acc = incrnancovariance();
 	for ( i = 0; i < data.length; i++ ) {
 		cov = acc( data[ i ][ 0 ], data[ i ][ 1 ] );
 	}
-	delta = abs( cov - expected );
-	tol = EPS * abs( expected );
-	t.equal( typeof cov, 'number', 'returns a number' );
-	t.ok( delta < tol, 'within tolerance. Actual: '+cov+'. Expected: '+expected+'. delta: '+delta+'. tol: '+tol+'.' );
+	t.strictEqual( typeof cov, 'number', 'returns expected value' );
+
+	expected = 14.0/3.0;
+	t.strictEqual( isAlmostSameValue( cov, expected, 0 ), true, 'returns expected value' );
 	t.end();
 });