Summary of Significant Accounting Policies (Tables)

12 Months Ended

Apr. 30, 2020

Accounting Policies [Abstract]

Estimated Useful Life of Property and Equipment

Depreciation is provided using the straight-line method over the estimated useful lives of the assets, which are as follows:

Asset Classification	Estimated Useful Life
Machinery and equipment	1-5 Years
Computer equipment	3-4 Years
Motor vehicles	4 Years
Leasehold improvements	5 Years or term of lease, if shorter

Schedule of Potential Dilutive Common Share Equivalents

Potential dilutive common share equivalents consist of:

	April 30,
	2020		2019		2018
Stock options and awards		2,320,677		1,784,338		388,366

Schedule of Cash Equivalents and Marketable Securities Measured at Fair Value

The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis as of April 30, 2020 and 2019:

	Level 1		Level 2		Level 3		Balance at April 30, 2020
Cash equivalents	$	650	$	—	$	—	$	650
Marketable securities:
Corporate debt securities		—		39,216		—		39,216
U.S. government agency securities		—		12,709		—		12,709
	$	650	$	51,925	$	—	$	52,575

	Level 1		Level 2		Level 3		Balance at April 30, 2019
Cash equivalents	$	30,044	$	1,962	$	—	$	32,006
Marketable securities:
Corporate debt securities		—		56,487		—		56,487
U.S. government agency securities		—		12,318		—		12,318
	$	30,044	$	70,767	$	—	$	100,811