Generate build infrastructure with hall, add tests

tests/geohash.scm

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+(define-module (test-geohash)
+  #:use-module (geohash)
+  #:use-module (ice-9 receive)
+  #:use-module (srfi srfi-64))
+
+(define (approximately? test-expr expected error)
+  (and (>= test-expr (- expected error))
+       (<= test-expr (+ expected error))))
+
+(test-begin "geohash")
+
+(test-equal "encode Jutland"
+  "u4pruy"
+  (encode 57.648 10.410 #:precision 6))
+
+(test-assert "decode Jutland"
+  (receive (lat lon) (decode "u4pruy")
+    (and (approximately? lat 57.648 0.0001)
+         (approximately? lon 10.410 0.0001))))
+
+(test-equal "encode Curitiba"
+  "6gkzwgjz"
+  (encode -25.38262 -49.26561 #:precision 8))
+
+(test-assert "decode Curitiba"
+  (receive (lat lon) (decode "6gkzwgjz")
+    (and (approximately? lat -25.38262 0.000001)
+         (approximately? lon -49.26561 0.000001))))
+
+(test-equal "neighbours"
+  '((n . "gbpb") (ne . "u000") (e . "spbp") (se . "spbn") (s . "ezzy") (sw . "ezzw") (w . "ezzx") (nw . "gbp8"))
+  (neighbours "ezzz"))
+
+(test-equal "encode max precision"
+  "wy85bj0hbp21"
+  (encode 37.25 123.75 #:precision 12))
+
+(test-equal "encode default precision"
+  "wy85bj"
+  (encode 37.25 123.75))
+
+(test-end)