diff --git a/src/spec-configuration/containerFeaturesOrder.ts b/src/spec-configuration/containerFeaturesOrder.ts
index ac0bbf149..d143d5dd7 100644
--- a/src/spec-configuration/containerFeaturesOrder.ts
+++ b/src/spec-configuration/containerFeaturesOrder.ts
@@ -24,7 +24,8 @@ export function computeFeatureInstallationOrder(config: DevContainerConfig, feat
     }
 }
 
-function computeOverrideInstallationOrder(config: DevContainerConfig, features: FeatureSet[]) {
+// Exported for unit tests.
+export function computeOverrideInstallationOrder(config: DevContainerConfig, features: FeatureSet[]) {
     // Starts with the automatic installation order.
     const automaticOrder = computeInstallationOrder(features);
 
@@ -42,7 +43,8 @@ function computeOverrideInstallationOrder(config: DevContainerConfig, features:
     return orderedFeatures.concat(features);
 }
 
-function computeInstallationOrder(features: FeatureSet[]) {
+// Exported for unit tests.
+export function computeInstallationOrder(features: FeatureSet[]) {
     const nodesById = features.map<FeatureNode>(feature => ({
         feature,
         before: new Set(),
diff --git a/src/test/container-features/containerFeaturesOrder.offline.test.ts b/src/test/container-features/containerFeaturesOrder.offline.test.ts
new file mode 100644
index 000000000..9e99f7dda
--- /dev/null
+++ b/src/test/container-features/containerFeaturesOrder.offline.test.ts
@@ -0,0 +1,113 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as assert from 'assert';
+import { ContainerError } from '../../spec-common/errors';
+import { FeatureSet } from '../../spec-configuration/containerFeaturesConfiguration';
+import { computeInstallationOrder, computeOverrideInstallationOrder } from '../../spec-configuration/containerFeaturesOrder';
+import { URI } from 'vscode-uri';
+
+describe('Container features install order', () => {
+
+    it('has stable order among independent features', () => {
+        assert.deepEqual(
+            computeInstallationOrder([
+                installAfter('C'),
+                installAfter('A'),
+                installAfter('B'),
+            ]).map(f => f.features[0].id),
+            ['A', 'B', 'C']
+        );
+    });
+
+    it('orders "installAfter" first in breadth-first order (tree)', () => {
+        assert.deepEqual(
+            computeInstallationOrder([
+                installAfter('A', 'B'),
+                installAfter('B', 'C'),
+                installAfter('C'),
+                installAfter('D', 'E'),
+                installAfter('E', 'C'),
+            ]).map(f => f.features[0].id),
+            ['C', 'B', 'E', 'A', 'D']
+        );
+    });
+
+    it('orders "installAfter" first in breadth-first order (DAG)', () => {
+        assert.deepEqual(
+            computeInstallationOrder([
+                installAfter('A', 'B', 'C'),
+                installAfter('B', 'C'),
+                installAfter('C'),
+                installAfter('D', 'C'),
+            ]).map(f => f.features[0].id),
+            ['C', 'B', 'D', 'A']
+        );
+    });
+
+    it('treats "installAfter" is a soft dependency', () => {
+        assert.deepEqual(
+            computeInstallationOrder([
+                installAfter('A', 'B', 'C'),
+                installAfter('B'),
+            ]).map(f => f.features[0].id),
+            ['B', 'A']
+        );
+    });
+
+    it('orders independent features last', () => {
+        assert.deepEqual(
+            computeInstallationOrder([
+                installAfter('A'),
+                installAfter('B', 'C'),
+                installAfter('C'),
+            ]).map(f => f.features[0].id),
+            ['C', 'B', 'A']
+        );
+    });
+
+    it('detects cycles', () => {
+        try {
+            computeInstallationOrder([
+                installAfter('A', 'B'),
+                installAfter('B'),
+                installAfter('C', 'D'),
+                installAfter('D', 'C'),
+            ]);
+            assert.fail('Cyclic dependency not detected.');
+        } catch (err) {
+            assert.ok(err instanceof ContainerError);
+            assert.ok(err.message.indexOf('cyclic'));
+        }
+    });
+
+    it('respects OverrideConfig', () => {
+        assert.deepEqual(
+            computeOverrideInstallationOrder(
+                { image: 'ubuntu', configFilePath: URI.from({ 'scheme': 'https' }), overrideFeatureInstallOrder: ['A', 'B', 'C'] },
+                [
+                    installAfter('A', 'C'),
+                    installAfter('B', 'C'),
+                    installAfter('C', 'D'),
+                ]).map(f => f.features[0].id),
+            ['A', 'B', 'C']
+        );
+    });
+
+    function installAfter(id: string, ...installAfter: string[]): FeatureSet {
+        return {
+            sourceInformation: {
+                type: 'local-cache',
+            },
+            features: [{
+                id,
+                name: id,
+                installAfter,
+                value: true,
+                included: true,
+            }],
+        };
+    }
+});
\ No newline at end of file
diff --git a/src/test/container-features/generateFeaturesConfig.offline.test.ts b/src/test/container-features/generateFeaturesConfig.offline.test.ts
index 0296e1866..bd3c3847e 100644
--- a/src/test/container-features/generateFeaturesConfig.offline.test.ts
+++ b/src/test/container-features/generateFeaturesConfig.offline.test.ts
@@ -4,7 +4,7 @@ import { createPlainLog, LogLevel, makeLog } from '../../spec-utils/log';
 import * as os from 'os';
 import * as path from 'path';
 import { mkdirpLocal } from '../../spec-utils/pfs';
-import { DevContainerConfig, DevContainerFeature } from '../../spec-configuration/configuration';
+import { DevContainerConfig } from '../../spec-configuration/configuration';
 import { URI } from 'vscode-uri';
 
 export const output = makeLog(createPlainLog(text => process.stdout.write(text), () => LogLevel.Trace));
@@ -38,25 +38,18 @@ describe('validate (offline) generateFeaturesConfig()', function () {
         const tmpFolder: string = path.join(os.tmpdir(), 'vsch', 'container-features', `${version}-${Date.now()}`);
         await mkdirpLocal(tmpFolder);
 
-        const features: DevContainerFeature[] = [
-            {
-                id: 'first',
-                options: {
-                    'version': 'latest'
-                },
-            },
-            {
-                id: 'second',
-                options: {
-                    'value': true
-                },
-            }
-        ];
 
         const config: DevContainerConfig = {
             configFilePath: URI.from({ 'scheme': 'https' }),
             dockerFile: '.',
-            features: features
+            features: {
+                first: {
+                    'version': 'latest'
+                },
+                second: {
+                    'value': true
+                },
+            },
         };
 
         const featuresConfig = await generateFeaturesConfig(params, tmpFolder, config, labels, localFeaturesFolder);