diff --git a/test/unit/interface.js b/test/unit/interface.js
new file mode 100644
index 0000000..be068a8
--- /dev/null
+++ b/test/unit/interface.js
@@ -0,0 +1,76 @@
+const u = require('../../src/utils')
+const ergogen = require('../../src/ergogen')
+
+const minimal = {
+    'points.zones.matrix': {
+        columns: {col: {}},
+        rows: {row: {}}
+    }
+}
+
+const full = {
+    'points.zones.matrix': {
+        columns: {col: {}},
+        rows: {row: {}}
+    },
+    'outlines.exports': {
+        export: [{
+            type: 'keys',
+            side: 'left',
+            size: 18
+        }],
+        _export: [{
+            type: 'keys',
+            side: 'left',
+            size: 18
+        }]
+    },
+    cases: {
+        export: [{
+            name: 'export',
+            extrude: 1
+        }],
+        _export: [{
+            name: 'export',
+            extrude: 1
+        }]
+    },
+    pcbs: {
+        export: {},
+        _export: {}
+    }
+}
+
+// to check whether the output has "private" exports
+const underscore = obj => {
+    for (const val of Object.values(obj)) {
+        for (const key of Object.keys(val)) {
+            if (key.startsWith('_')) return true
+        }
+    }
+    return false
+}
+
+
+describe('Interface', function() {
+
+    it('minimal', function() {
+        underscore(ergogen.process(minimal)).should.be.false
+    })
+
+    it('production', function() {
+        underscore(ergogen.process(full, false)).should.be.false
+    })
+    
+    it('debug', function() {
+        underscore(ergogen.process(full, true)).should.be.true
+    })
+
+    it('logging', function() {
+        const flag = {value: false}
+        const logger = msg => { flag.value = true }
+        ergogen.process(full, false, logger)
+        flag.value.should.be.true
+    })
+
+})
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