module Kernel

static VALUE
f_BigDecimal(int argc, VALUE *argv, VALUE self)
{
    VALUE val, digs_v, opts = Qnil;
    argc = rb_scan_args(argc, argv, "11:", &val, &digs_v, &opts);
    int exception = opts_exception_p(opts);

    size_t digs = SIZE_MAX; /* this means digs is omitted */
    if (argc > 1) {
        digs_v = rb_to_int(digs_v);
        if (FIXNUM_P(digs_v)) {
            long n = FIX2LONG(digs_v);
            if (n < 0)
                goto negative_digs;
            digs = (size_t)n;
        }
        else {
            if (RBIGNUM_NEGATIVE_P(digs_v)) {
              negative_digs:
                if (!exception)
                    return Qnil;
                rb_raise(rb_eArgError, "negative precision");
            }
            digs = NUM2SIZET(digs_v);
        }
    }

    return rb_convert_to_BigDecimal(val, digs, exception);
}

Returns the BigDecimal converted from value with a precision of ndigits decimal digits.

When ndigits is less than the number of significant digits in the value, the result is rounded to that number of digits, according to the current rounding mode; see BigDecimal.mode.

When ndigits is 0, the number of digits to correctly represent a float number is determined automatically.

Returns value converted to a BigDecimal, depending on the type of value:

• Integer, Float, Rational, Complex, or BigDecimal: converted directly:

  # Integer, Complex, Float, or BigDecimal value does not require ndigits; ignored if given.
  BigDecimal(2)                     # => 0.2e1
  BigDecimal(Complex(2, 0))         # => 0.2e1
  BigDecimal(BigDecimal(2))         # => 0.2e1
  BigDecimal(2.0)                   # => 0.2e1
  # Rational value requires ndigits.
  BigDecimal(Rational(2, 1), 0)     # => 0.2e1
  

• String: converted by parsing if it contains an integer or floating-point literal; leading and trailing whitespace is ignored:

  # String does not require ndigits; ignored if given.
  BigDecimal('2')     # => 0.2e1
  BigDecimal('2.0')   # => 0.2e1
  BigDecimal('0.2e1') # => 0.2e1
  BigDecimal(' 2.0 ') # => 0.2e1
  

• Other type that responds to method :to_str: first converted to a string, then converted to a BigDecimal, as above.

• Other type:

  • Raises an exception if keyword argument exception is true.

  • Returns nil if keyword argument exception is false.

Raises an exception if value evaluates to a Float and digits is larger than Float::DIG + 1.

# File vendor/bundle/ruby/3.4.0/gems/minitest-5.26.0/lib/minitest/spec.rb, line 86
def describe desc, *additional_desc, &block # :doc:
  stack = Minitest::Spec.describe_stack
  is_spec_class = Class === self && kind_of?(Minitest::Spec::DSL)
  name  = [stack.last, desc, *additional_desc]
  name.prepend self if stack.empty? && is_spec_class
  sclas =
    stack.last                 \
    || (is_spec_class && self) \
    || Minitest::Spec.spec_type(desc, *additional_desc)

  cls = sclas.create name.compact.join("::"), desc

  stack.push cls
  cls.class_eval(&block)
  stack.pop
  cls
end

Describe a series of expectations for a given target desc.

Defines a test class subclassing from either Minitest::Spec or from the surrounding describe’s class. The surrounding class may subclass Minitest::Spec manually in order to easily share code:

class MySpec < Minitest::Spec
  # ... shared code ...
end

class TestStuff < MySpec
  it "does stuff" do
    # shared code available here
  end
  describe "inner stuff" do
    it "still does stuff" do
      # ...and here
    end
  end
end

For more information on getting started with writing specs, see:

www.rubyinside.com/a-minitestspec-tutorial-elegant-spec-style-testing-that-comes-with-ruby-5354.html

For some suggestions on how to improve your specs, try:

betterspecs.org

but do note that several items there are debatable or specific to rspec.

For more information about expectations, see Minitest::Expectations.