diff --git a/src/testdir/test_float_func.vim b/src/testdir/test_float_func.vim
index f407f40..17b5cda 100644
--- a/src/testdir/test_float_func.vim
+++ b/src/testdir/test_float_func.vim
@@ -6,6 +6,8 @@
 func Test_abs()
   call assert_equal('1.23', string(abs(1.23)))
   call assert_equal('1.23', string(abs(-1.23)))
+  eval -1.23->abs()->string()->assert_equal('1.23')
+
   call assert_equal('0.0', string(abs(0.0)))
   call assert_equal('0.0', string(abs(1.0/(1.0/0.0))))
   call assert_equal('0.0', string(abs(-1.0/(1.0/0.0))))
@@ -22,6 +24,7 @@
 func Test_sqrt()
   call assert_equal('0.0', string(sqrt(0.0)))
   call assert_equal('1.414214', string(sqrt(2.0)))
+  eval 2.0->sqrt()->string()->assert_equal('1.414214')
   call assert_equal('inf', string(sqrt(1.0/0.0)))
   call assert_equal('nan', string(sqrt(-1.0)))
   call assert_equal('nan', string(sqrt(0.0/0.0)))
@@ -31,6 +34,7 @@
 func Test_log()
   call assert_equal('0.0', string(log(1.0)))
   call assert_equal('-0.693147', string(log(0.5)))
+  eval 0.5->log()->string()->assert_equal('-0.693147')
   call assert_equal('-inf', string(log(0.0)))
   call assert_equal('nan', string(log(-1.0)))
   call assert_equal('inf', string(log(1.0/0.0)))
@@ -42,6 +46,7 @@
   call assert_equal('0.0', string(log10(1.0)))
   call assert_equal('2.0', string(log10(100.0)))
   call assert_equal('2.079181', string(log10(120.0)))
+  eval 120.0->log10()->string()->assert_equal('2.079181')
   call assert_equal('-inf', string(log10(0.0)))
   call assert_equal('nan', string(log10(-1.0)))
   call assert_equal('inf', string(log10(1.0/0.0)))
@@ -53,6 +58,7 @@
   call assert_equal('1.0', string(exp(0.0)))
   call assert_equal('7.389056', string(exp(2.0)))
   call assert_equal('0.367879', string(exp(-1.0)))
+  eval -1.0->exp()->string()->assert_equal('0.367879')
   call assert_equal('inf', string(exp(1.0/0.0)))
   call assert_equal('0.0', string(exp(-1.0/0.0)))
   call assert_equal('nan', string(exp(0.0/0.0)))
@@ -63,6 +69,7 @@
   call assert_equal('0.0', string(sin(0.0)))
   call assert_equal('0.841471', string(sin(1.0)))
   call assert_equal('-0.479426', string(sin(-0.5)))
+  eval -0.5->sin()->string()->assert_equal('-0.479426')
   call assert_equal('nan', string(sin(0.0/0.0)))
   call assert_equal('nan', string(sin(1.0/0.0)))
   call assert_equal('0.0', string(sin(1.0/(1.0/0.0))))
@@ -73,6 +80,8 @@
 func Test_asin()
   call assert_equal('0.0', string(asin(0.0)))
   call assert_equal('1.570796', string(asin(1.0)))
+  eval 1.0->asin()->string()->assert_equal('1.570796')
+
   call assert_equal('-0.523599', string(asin(-0.5)))
   call assert_equal('nan', string(asin(1.1)))
   call assert_equal('nan', string(asin(1.0/0.0)))
@@ -84,6 +93,7 @@
   call assert_equal('0.0', string(sinh(0.0)))
   call assert_equal('0.521095', string(sinh(0.5)))
   call assert_equal('-1.026517', string(sinh(-0.9)))
+  eval -0.9->sinh()->string()->assert_equal('-1.026517')
   call assert_equal('inf', string(sinh(1.0/0.0)))
   call assert_equal('-inf', string(sinh(-1.0/0.0)))
   call assert_equal('nan', string(sinh(0.0/0.0)))
@@ -94,6 +104,7 @@
   call assert_equal('1.0', string(cos(0.0)))
   call assert_equal('0.540302', string(cos(1.0)))
   call assert_equal('0.877583', string(cos(-0.5)))
+  eval -0.5->cos()->string()->assert_equal('0.877583')
   call assert_equal('nan', string(cos(0.0/0.0)))
   call assert_equal('nan', string(cos(1.0/0.0)))
   call assert_fails('call cos("")', 'E808:')
@@ -103,6 +114,7 @@
   call assert_equal('1.570796', string(acos(0.0)))
   call assert_equal('0.0', string(acos(1.0)))
   call assert_equal('3.141593', string(acos(-1.0)))
+  eval -1.0->acos()->string()->assert_equal('3.141593')
   call assert_equal('2.094395', string(acos(-0.5)))
   call assert_equal('nan', string(acos(1.1)))
   call assert_equal('nan', string(acos(1.0/0.0)))
@@ -113,6 +125,7 @@
 func Test_cosh()
   call assert_equal('1.0', string(cosh(0.0)))
   call assert_equal('1.127626', string(cosh(0.5)))
+  eval 0.5->cosh()->string()->assert_equal('1.127626')
   call assert_equal('inf', string(cosh(1.0/0.0)))
   call assert_equal('inf', string(cosh(-1.0/0.0)))
   call assert_equal('nan', string(cosh(0.0/0.0)))
@@ -123,6 +136,7 @@
   call assert_equal('0.0', string(tan(0.0)))
   call assert_equal('0.546302', string(tan(0.5)))
   call assert_equal('-0.546302', string(tan(-0.5)))
+  eval -0.5->tan()->string()->assert_equal('-0.546302')
   call assert_equal('nan', string(tan(1.0/0.0)))
   call assert_equal('nan', string(cos(0.0/0.0)))
   call assert_equal('0.0', string(tan(1.0/(1.0/0.0))))
@@ -134,6 +148,7 @@
   call assert_equal('0.0', string(atan(0.0)))
   call assert_equal('0.463648', string(atan(0.5)))
   call assert_equal('-0.785398', string(atan(-1.0)))
+  eval -1.0->atan()->string()->assert_equal('-0.785398')
   call assert_equal('1.570796', string(atan(1.0/0.0)))
   call assert_equal('-1.570796', string(atan(-1.0/0.0)))
   call assert_equal('nan', string(atan(0.0/0.0)))
@@ -144,6 +159,7 @@
   call assert_equal('-2.356194', string(atan2(-1, -1)))
   call assert_equal('2.356194', string(atan2(1, -1)))
   call assert_equal('0.0', string(atan2(1.0, 1.0/0.0)))
+  eval 1.0->atan2(1.0/0.0)->string()->assert_equal('0.0')
   call assert_equal('1.570796', string(atan2(1.0/0.0, 1.0)))
   call assert_equal('nan', string(atan2(0.0/0.0, 1.0)))
   call assert_fails('call atan2("", -1)', 'E808:')
@@ -154,6 +170,7 @@
   call assert_equal('0.0', string(tanh(0.0)))
   call assert_equal('0.462117', string(tanh(0.5)))
   call assert_equal('-0.761594', string(tanh(-1.0)))
+  eval -1.0->tanh()->string()->assert_equal('-0.761594')
   call assert_equal('1.0', string(tanh(1.0/0.0)))
   call assert_equal('-1.0', string(tanh(-1.0/0.0)))
   call assert_equal('nan', string(tanh(0.0/0.0)))
@@ -164,6 +181,7 @@
   call assert_equal('0.13', string(fmod(12.33, 1.22)))
   call assert_equal('-0.13', string(fmod(-12.33, 1.22)))
   call assert_equal('nan', string(fmod(1.0/0.0, 1.0)))
+  eval (1.0/0.0)->fmod(1.0)->string()->assert_equal('nan')
   " On Windows we get "nan" instead of 1.0, accept both.
   let res = string(fmod(1.0, 1.0/0.0))
   if res != 'nan'
@@ -177,6 +195,7 @@
 func Test_pow()
   call assert_equal('1.0', string(pow(0.0, 0.0)))
   call assert_equal('8.0', string(pow(2.0, 3.0)))
+  eval 2.0->pow(3.0)->string()->assert_equal('8.0')
   call assert_equal('nan', string(pow(2.0, 0.0/0.0)))
   call assert_equal('nan', string(pow(0.0/0.0, 3.0)))
   call assert_equal('nan', string(pow(0.0/0.0, 3.0)))
@@ -192,6 +211,7 @@
   call assert_equal('1.0', string(str2float(' 1.0 ')))
   call assert_equal('1.23', string(str2float('1.23')))
   call assert_equal('1.23', string(str2float('1.23abc')))
+  eval '1.23abc'->str2float()->string()->assert_equal('1.23')
   call assert_equal('1.0e40', string(str2float('1e40')))
   call assert_equal('-1.23', string(str2float('-1.23')))
   call assert_equal('1.23', string(str2float(' + 1.23 ')))
@@ -228,6 +248,7 @@
   call assert_equal(1, float2nr(1.234))
   call assert_equal(123, float2nr(1.234e2))
   call assert_equal(12, float2nr(123.4e-1))
+  eval 123.4e-1->float2nr()->assert_equal(12)
   let max_number = 1/0
   let min_number = -max_number
   call assert_equal(max_number/2+1, float2nr(pow(2, 62)))
@@ -242,6 +263,7 @@
   call assert_equal('2.0', string(floor(2.0)))
   call assert_equal('2.0', string(floor(2.11)))
   call assert_equal('2.0', string(floor(2.99)))
+  eval 2.99->floor()->string()->assert_equal('2.0')
   call assert_equal('-3.0', string(floor(-2.11)))
   call assert_equal('-3.0', string(floor(-2.99)))
   call assert_equal('nan', string(floor(0.0/0.0)))
@@ -255,6 +277,7 @@
   call assert_equal('3.0', string(ceil(2.11)))
   call assert_equal('3.0', string(ceil(2.99)))
   call assert_equal('-2.0', string(ceil(-2.11)))
+  eval -2.11->ceil()->string()->assert_equal('-2.0')
   call assert_equal('-2.0', string(ceil(-2.99)))
   call assert_equal('nan', string(ceil(0.0/0.0)))
   call assert_equal('inf', string(ceil(1.0/0.0)))
@@ -266,6 +289,7 @@
   call assert_equal('2.0', string(round(2.1)))
   call assert_equal('3.0', string(round(2.5)))
   call assert_equal('3.0', string(round(2.9)))
+  eval 2.9->round()->string()->assert_equal('3.0')
   call assert_equal('-2.0', string(round(-2.1)))
   call assert_equal('-3.0', string(round(-2.5)))
   call assert_equal('-3.0', string(round(-2.9)))
@@ -279,6 +303,7 @@
   call assert_equal('2.0', string(trunc(2.1)))
   call assert_equal('2.0', string(trunc(2.5)))
   call assert_equal('2.0', string(trunc(2.9)))
+  eval 2.9->trunc()->string()->assert_equal('2.0')
   call assert_equal('-2.0', string(trunc(-2.1)))
   call assert_equal('-2.0', string(trunc(-2.5)))
   call assert_equal('-2.0', string(trunc(-2.9)))
@@ -291,6 +316,7 @@
 func Test_isinf()
   call assert_equal(1, isinf(1.0/0.0))
   call assert_equal(-1, isinf(-1.0/0.0))
+  eval (-1.0/0.0)->isinf()->assert_equal(-1)
   call assert_false(isinf(1.0))
   call assert_false(isinf(0.0/0.0))
   call assert_false(isinf('a'))
@@ -302,6 +328,7 @@
   call assert_true(isnan(0.0/0.0))
   call assert_false(isnan(1.0))
   call assert_false(isnan(1.0/0.0))
+  eval (1.0/0.0)->isnan()->assert_false()
   call assert_false(isnan(-1.0/0.0))
   call assert_false(isnan('a'))
   call assert_false(isnan([]))