diff --git a/src/selectors/__test__/allExpenses-spec.js b/src/selectors/__test__/allExpenses-spec.js
new file mode 100644
index 0000000..f1ef3d2
--- /dev/null
+++ b/src/selectors/__test__/allExpenses-spec.js
@@ -0,0 +1,23 @@
+import selector from '../allExpenses'
+
+describe('allExpenses selector', () => {
+
+  it('combines all expenses into a single array', () => {
+    const state = {
+      project: {
+        members: [
+          {expenses: [1,2]},
+          {expenses: [3,4]}
+        ]
+      }
+    }
+    expect(selector(state)).toEqual([1,2,3,4])
+  })
+
+  it('handles a project with no members', () => {
+    const state = {
+      project: {members: []}
+    }
+    expect(selector(state)).toEqual([])
+  })
+})
diff --git a/src/selectors/__test__/allExpensesMap-spec.js b/src/selectors/__test__/allExpensesMap-spec.js
new file mode 100644
index 0000000..4b6187d
--- /dev/null
+++ b/src/selectors/__test__/allExpensesMap-spec.js
@@ -0,0 +1,28 @@
+import selector from '../allExpensesMap'
+
+describe('allExpensesMap selector', () => {
+
+  it('combines all expenses into a single map', () => {
+    const state = {
+      project: {
+        members: [
+          {expenses: [{slug: 1}, {slug: 2}]},
+          {expenses: [{slug: 3}, {slug: 4}]}
+        ]
+      }
+    }
+    expect([...selector(state)]).toEqual([
+      [1, {slug: 1}],
+      [2, {slug: 2}],
+      [3, {slug: 3}],
+      [4, {slug: 4}]
+    ])
+  })
+
+  it('handles a project with no members', () => {
+    const state = {
+      project: {members: []}
+    }
+    expect([...selector(state)]).toEqual([])
+  })
+})