Update Huffman tests

include/inflate.h

@@ -25,8 +25,11 @@ typedef struct huffman {
 /* Reset the position state variable */
 void reset_pos();
 
-/* Create a Huffman mapping from a sequence of lengths. */
-huffman_t *make_huffman(int *lens, int *alphabet, int n_symbols);
+/*
+ * Create a Huffman mapping from a sequence of lengths. 
+ * The alphabet used is (0, 1, ..., n_symbols - 1) 
+ */
+huffman_t *make_huffman(int *lens, int n_symbols);
 
 /* Clean up a heap allocated Huffman map */
 void destroy_huffman(huffman_t *hf);

tests/inflate_test.cpp

@@ -78,10 +78,79 @@ TEST (BufferTests, RevStreamOrderTest) {
     ASSERT_EQ (get_n_bits((char *) buf, 6, true), 36); 
 }
 
+/* Test making a huffman tree from a sequence of lengths */ 
+TEST (HuffmanTests, TestMakeHuffman) {
+    int n_symbols = 8; 
+    int lens[8] = {3, 3, 3, 3, 3, 2, 4, 4}; 
+
+    huffman_t *hf = make_huffman(lens, n_symbols); 
+    
+    int bl_counts[MAX_LENGTH + 1] = {0, 0, 1, 5, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; 
+
+    /* Check bl_counts */
+    for (int i = 0; i < MAX_LENGTH + 1; i++) { 
+        ASSERT_EQ (hf->bl_counts[i], bl_counts[i]);     
+    }
+
+    /* 
+     * Check min_codes for entries with non-zero bl_count 
+     * It doesn't really matter what the other entries are. 
+     */ 
+    ASSERT_EQ (hf->min_codes[2], 0); 
+    ASSERT_EQ (hf->min_codes[3], 2);
+    ASSERT_EQ (hf->min_codes[4], 14);  
+
+    /* Check that the alphabet arrays were populated correctly. */ 
+    ASSERT_EQ (hf->alphabet[2][0], 5);
+    for (int i = 0; i < 5; i++) ASSERT_EQ (hf->alphabet[3][i], i); 
+    ASSERT_EQ (hf->alphabet[4][0], 6);
+    ASSERT_EQ (hf->alphabet[4][1], 7);
+
+    destroy_huffman(hf); 
+}
+
+/* 
+ * Test that make_huffman does not assign a code to symbols with 
+ * a length of 0. 
+ */
+TEST (HuffmanTests, TestMakeHuffmanZeroLens) { 
+    int n_symbols = 8; 
+    int lens[8] = {1, 0, 2, 3, 3, 0, 4, 3};
+
+    huffman_t *hf = make_huffman(lens, n_symbols); 
+    
+    int bl_counts[MAX_LENGTH + 1] = {0, 1, 1, 3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; 
+    
+    /* Check bl_counts */
+    for (int i = 0; i < MAX_LENGTH + 1; i++) {
+        ASSERT_EQ (hf->bl_counts[i], bl_counts[i]); 
+    }
+
+    /* Check min_codes */
+    ASSERT_EQ (hf->min_codes[1], 0);
+    ASSERT_EQ (hf->min_codes[2], 2);
+    ASSERT_EQ (hf->min_codes[3], 6);
+    ASSERT_EQ (hf->min_codes[4], 18);
+
+    /* Check alphabet. */
+    ASSERT_EQ (hf->alphabet[1][0], 0);
+
+    /* 1 and 5 are not used! (length = 0) */
+    ASSERT_EQ (hf->alphabet[2][0], 2);
+
+    ASSERT_EQ (hf->alphabet[3][0], 3);
+    ASSERT_EQ (hf->alphabet[3][1], 4); 
+    ASSERT_EQ (hf->alphabet[3][2], 7); 
+
+    ASSERT_EQ (hf->alphabet[4][0], 6); 
+
+    destroy_huffman(hf); 
+}
+
 // TODO 
-TEST (HuffmanTests, TestMakeHuffman) {}
+TEST (HuffmanTests, TestReadChunk) {
 
-TEST (HuffmanTests, TestReadChunk) {}
+}
 
 TEST (HuffmanTests, TestReadLens) {}