diff --git a/publicodes/test/cycles.test.js b/publicodes/test/cycles.test.js
new file mode 100644
index 000000000..92ab91e19
--- /dev/null
+++ b/publicodes/test/cycles.test.js
@@ -0,0 +1,65 @@
+import { expect } from 'chai'
+import dedent from 'dedent-js'
+
+import { hasCycles } from '../source/cyclesLib'
+
+describe('Cyclic dependencies detector 3000 ™', () => {
+	it('should detect the trivial formule cycle', () => {
+		const rules = dedent`
+			a:
+				formule: a + 1
+		`
+		const cycles = hasCycles(rules)
+		expect(cycles).to.deep.equal([['a']])
+	})
+
+	it('should detect the trivial replace cycle', () => {
+		const rules = dedent`
+			a:
+				remplace: a
+		`
+		const cycles = hasCycles(rules)
+		expect(cycles).to.deep.equal([['a']])
+	})
+
+	it('should detect nested and parallel formule cycles', () => {
+		const rules = dedent`
+			a:
+				formule: b + 1
+			b:
+				formule: c + d + 1
+			c:
+				formule: a + 1
+			d:
+				formule: b + 1
+		`
+		const cycles = hasCycles(rules)
+		expect(cycles).to.deep.equal([['d', 'c', 'b', 'a']])
+	})
+
+	it('should not detect 1 level formule + remplace', () => {
+		const rules = dedent`
+			b:
+				formule: c + 1
+				remplace: c
+			c:
+				formule: 0
+		`
+		const cycles = hasCycles(rules)
+		expect(cycles).to.be.empty
+	})
+
+	it('should detect a 2 levels formuleX2 + remplace (but why? 😢)', () => {
+		const rules = dedent`
+			a:
+				formule: b + 1
+				remplace: c
+			b:
+				formule: c + 1
+			c:
+				formule: 0
+		`
+		const cycles = hasCycles(rules)
+		expect(cycles).to.deep.equal([['c', 'b', 'a']])
+	})
+})