diff --git a/src/MusicTheory.jl b/src/MusicTheory.jl
index 3d676c8..cb0b465 100644
--- a/src/MusicTheory.jl
+++ b/src/MusicTheory.jl
@@ -13,9 +13,11 @@ export Major_2nd, Minor_2nd, Major_3rd, Minor_3rd, Perfect_4th, Perfect_5th,
 export Scale
 export major_scale, natural_minor_scale, melodic_minor_scale, harmonic_minor_scale
 
+export Chord
 
 
 include("notes.jl")
 include("intervals.jl")
 include("scales.jl")
+include("chords.jl")
 end
diff --git a/src/notes.jl b/src/notes.jl
index 6adeb66..8dc027e 100644
--- a/src/notes.jl
+++ b/src/notes.jl
@@ -79,7 +79,7 @@ end
 PitchClass(n::PitchClass) = n
 
 
-
+Base.isless(n1::PitchClass, n2::PitchClass) = semitone(n1) < semitone(n2)
 Base.isless(n1::Pitch, n2::Pitch) = semitone(n1) < semitone(n2)
 
 
diff --git a/test/intervals.jl b/test/intervals.jl
new file mode 100644
index 0000000..feb600f
--- /dev/null
+++ b/test/intervals.jl
@@ -0,0 +1,20 @@
+@testset "Intervals" begin
+    @test Interval(C[4], D[4]) == Interval(1, Major)
+    @test Interval(E[4], C[4]) == Interval(2, Major)
+    @test Interval(B[4], C[4]) == Interval(6, Major)
+
+    @test Interval(B[4], C[5]) == Interval(1, Minor)
+
+    @test Interval(B[4], B[4]) == Interval(0, Perfect)
+    @test Interval(B[4], B[5]) == Interval(7, Perfect)
+
+end
+
+@testset "Adding intervals" begin
+    @test C + Interval(1, Major) == D
+    @test C + Interval(2, Major) == E
+    @test C + Interval(6, Major) == B
+
+    @test C[4] + Interval(1, Major) == D[4]
+    @test B[4] + Interval(1, Major) == C♯[5]
+end
\ No newline at end of file
diff --git a/test/notes.jl b/test/notes.jl
new file mode 100644
index 0000000..de23c79
--- /dev/null
+++ b/test/notes.jl
@@ -0,0 +1,9 @@
+using MusicTheory.NoteNames
+
+@testset "Notes" begin
+    note = C[4]
+
+    @test PitchClass(note) == C
+    @test accidental(note) == ♮
+    @test octave(note) == 4
+end
diff --git a/test/scales.jl b/test/scales.jl
new file mode 100644
index 0000000..cdcc12b
--- /dev/null
+++ b/test/scales.jl
@@ -0,0 +1,8 @@
+@testset "Scales" begin
+
+    scale = Scale(C[4], major_scale)
+
+    scale_tones = Base.Iterators.take(scale, 8) |> collect
+    @test scale_tones == Pitch[C[4], D[4], E[4], F[4], G[4], A[4], B[4], C[5]]
+
+end
\ No newline at end of file