1 files changed, 80 insertions, 0 deletions
diff --git a/common/probdist/weighted_dist_test.go b/common/probdist/weighted_dist_test.go
new file mode 100644
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--- /dev/null
+++ b/common/probdist/weighted_dist_test.go
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+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package probdist
+
+import (
+	"fmt"
+	"testing"
+
+	"git.torproject.org/pluggable-transports/obfs4.git/common/drbg"
+)
+
+const debug = false
+
+func TestWeightedDist(t *testing.T) {
+	seed, err := drbg.NewSeed()
+	if err != nil {
+		t.Fatal("failed to generate a DRBG seed:", err)
+	}
+
+	const nrTrials = 1000000
+
+	hist := make([]int, 1000)
+
+	w := New(seed, 0, 999, true)
+	if debug {
+		// Dump a string representation of the probability table.
+		fmt.Println("Table:")
+		var sum float64
+		for _, weight := range w.weights {
+			sum += weight
+		}
+		for i, weight := range w.weights {
+			p := weight / sum
+			if p > 0.000001 { // Filter out tiny values.
+				fmt.Printf(" [%d]: %f\n", w.minValue+w.values[i], p)
+			}
+		}
+		fmt.Println()
+	}
+
+	for i := 0; i < nrTrials; i++ {
+		value := w.Sample()
+		hist[value]++
+	}
+
+	if debug {
+		fmt.Println("Generated:")
+		for value, count := range hist {
+			if count != 0 {
+				p := float64(count) / float64(nrTrials)
+				fmt.Printf(" [%d]: %f (%d)\n", value, p, count)
+			}
+		}
+	}
+}